/*
 * Copyright (c) 2019-2026 YZF Sudoku and its developers. All rights reserved.
 * Contact: 63160007@qq.com. Full notice: COPYRIGHT.md.
 * YZF Sudoku UI 基础层。
 * 统一正式界面组件、响应式弹层与可访问状态；盘面、候选、链图和技巧高亮规则仍由业务样式维护。
 */
:root {
  --yzf-radius-s: 7px;
  --yzf-radius-m: 11px;
  --yzf-radius-l: 16px;
  --yzf-space-1: 4px;
  --yzf-space-2: 8px;
  --yzf-space-3: 12px;
  --yzf-space-4: 16px;
  --yzf-touch-target: 36px;
  --yzf-dialog-shadow: 0 24px 80px rgba(15, 23, 42, .30);
  --yzf-backdrop: rgba(15, 23, 42, .42);
}

:is(.yzf-diagnostics-dialog, .yzf-task-center-dialog, .yzf-workspace-dialog, .app-hub-dialog) {
  position: fixed;
  inset: 50% auto auto 50%;
  width: min(var(--yzf-dialog-width, 680px), calc(100vw - 24px));
  max-height: var(--yzf-dialog-max-height, min(84vh, 820px));
  margin: 0;
  padding: 0;
  transform: translate(-50%, -50%);
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--border-strong, #bdcadb) 80%, transparent);
  border-radius: var(--yzf-radius-l);
  background: var(--surface, #fff);
  color: var(--ink);
  box-shadow: var(--yzf-dialog-shadow);
}

dialog[data-yzf-panel="1"][data-yzf-panel-placement="responsive"]::backdrop {
  background: var(--yzf-backdrop);
  backdrop-filter: blur(2px);
}

button[data-yzf-variant] {
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}
button[data-yzf-size="s"] { min-height: 30px; }
button[data-yzf-size="m"] { min-height: var(--yzf-touch-target); }
button[data-yzf-size="l"] { min-height: 42px; }
button[data-yzf-variant^="alert"]:not(.primary):hover:not(:disabled) {
  border-color: color-mix(in srgb, var(--delete) 55%, var(--border));
  color: var(--delete);
}
button[data-yzf-variant="icon-tertiary"] { margin: 0; }

label[data-yzf-setting-row="1"] {
  accent-color: var(--accent);
}


.yzf-diagnostics-dialog {
  --yzf-dialog-width: 720px;
  --yzf-dialog-max-height: min(84vh, 820px);
}
.yzf-diagnostics-panel {
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr) auto;
  min-height: min(540px, 80vh);
  max-height: min(84vh, 820px);
}
.yzf-panel-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--yzf-space-3);
  padding: var(--yzf-space-3) var(--yzf-space-4);
  border-bottom: 1px solid var(--border);
  background: var(--surface, #fff);
}
.yzf-panel-header strong { font-size: 16px; }
.yzf-panel-header p {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.5;
}
.yzf-panel-close {
  flex: 0 0 auto;
  width: 32px;
  height: 32px;
  min-height: 32px;
  margin: 0;
  padding: 0;
  border-radius: 999px;
  font-size: 20px;
  line-height: 1;
}
.yzf-diagnostics-summary {
  padding: 10px var(--yzf-space-4);
  border-bottom: 1px solid var(--border);
  background: var(--surface-soft, #f7f9fc);
  color: var(--muted);
  font-size: 12px;
}
.yzf-diagnostics-output {
  width: auto;
  max-height: none;
  min-height: 260px;
  margin: var(--yzf-space-3) var(--yzf-space-4);
  padding: var(--yzf-space-3);
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: var(--yzf-radius-m);
  background: var(--surface-soft, #f7f9fc);
  color: var(--ink);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  user-select: text;
  font-size: 11.5px;
  line-height: 1.55;
}
.yzf-panel-actions {
  display: flex;
  align-items: center;
  gap: var(--yzf-space-2);
  padding: var(--yzf-space-3) var(--yzf-space-4) max(var(--yzf-space-3), env(safe-area-inset-bottom));
  border-top: 1px solid var(--border);
  background: var(--surface, #fff);
}
.yzf-panel-actions button { margin: 0; }
.yzf-panel-spacer { flex: 1; }

@media (max-width: 680px) and (orientation: portrait) {
  dialog[data-yzf-panel="1"][data-yzf-panel-placement="responsive"] {
    inset: auto 0 0;
    width: 100%;
    max-width: none;
    max-height: min(90dvh, 860px);
    margin: 0;
    transform: none;
    border-width: 1px 0 0;
    border-radius: var(--yzf-radius-l) var(--yzf-radius-l) 0 0;
  }
  .yzf-diagnostics-panel { min-height: min(660px, 88dvh); }
  .yzf-diagnostics-output { min-height: 220px; }
}

@media (max-height: 620px) and (orientation: landscape) {
  dialog[data-yzf-panel="1"][data-yzf-panel-placement="responsive"] {
    inset: 0 0 0 auto;
    width: min(520px, 58vw);
    max-width: none;
    max-height: 100dvh;
    height: 100dvh;
    margin: 0;
    transform: none;
    border-width: 0 0 0 1px;
    border-radius: var(--yzf-radius-l) 0 0 var(--yzf-radius-l);
  }
  .yzf-diagnostics-panel { min-height: 100%; max-height: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  dialog[data-yzf-panel="1"],
  dialog[data-yzf-panel="1"]::backdrop { scroll-behavior: auto; }
}

.yzf-task-center-entry { --status-color: #64748b; }
.yzf-task-center-dialog {
  --yzf-dialog-width: 620px;
  --yzf-dialog-max-height: min(82vh, 760px);
}
.yzf-task-center-panel {
  display: grid;
  grid-template-rows: auto minmax(180px, 1fr) auto;
  min-height: min(440px, 76vh);
  max-height: min(82vh, 760px);
}
.yzf-task-list {
  display: grid;
  align-content: start;
  gap: var(--yzf-space-2);
  padding: var(--yzf-space-3) var(--yzf-space-4);
  overflow: auto;
  background: var(--surface-soft, #f7f9fc);
}
.yzf-task-empty {
  display: grid;
  place-items: center;
  min-height: 180px;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}
.yzf-task-row {
  --task-tone: #2563eb;
  display: grid;
  gap: 9px;
  padding: 11px 12px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--task-tone);
  border-radius: var(--yzf-radius-m);
  background: var(--surface, #fff);
}
.yzf-task-row[data-tone="ok"] { --task-tone: #16a34a; }
.yzf-task-row[data-tone="warn"] { --task-tone: #d97706; }
.yzf-task-row[data-tone="error"] { --task-tone: #dc2626; }
.yzf-task-row-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--yzf-space-3);
}
.yzf-task-copy { min-width: 0; }
.yzf-task-copy strong { font-size: 13px; }
.yzf-task-copy p {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 11.5px;
  line-height: 1.45;
  overflow-wrap: anywhere;
}
.yzf-task-meta {
  display: grid;
  justify-items: end;
  flex: 0 0 auto;
  gap: 2px;
  color: var(--muted);
  font-size: 10.5px;
}
.yzf-task-state {
  color: var(--task-tone);
  font-weight: 800;
}
.yzf-task-row progress {
  width: 100%;
  height: 7px;
  overflow: hidden;
  border: 0;
  border-radius: 999px;
  accent-color: var(--task-tone);
}
.yzf-task-center-panel > .yzf-panel-actions > [data-yzf-task-summary],

@media (max-width: 680px) and (orientation: portrait) {
  .yzf-task-center-panel { min-height: min(620px, 86dvh); }
}
@media (max-height: 620px) and (orientation: landscape) {
  .yzf-task-center-panel { min-height: 100%; max-height: 100%; }
}

/* 工作现场中心。 */
.yzf-workspace-dialog {
  --yzf-dialog-width: 680px;
  --yzf-dialog-max-height: min(84vh, 820px);
}
.yzf-workspace-panel {
  display: grid;
  grid-template-rows: auto minmax(220px, 1fr) auto;
  min-height: min(520px, 80vh);
  max-height: min(84vh, 820px);
}
.yzf-workspace-content {
  display: grid;
  align-content: start;
  gap: var(--yzf-space-3);
  padding: var(--yzf-space-3) var(--yzf-space-4);
  overflow: auto;
  background: var(--surface-soft, #f7f9fc);
}
.yzf-workspace-loading {
  display: grid;
  place-items: center;
  min-height: 180px;
  color: var(--muted);
  font-size: 13px;
}
.yzf-workspace-card {
  display: flex;
  align-items: center;
  gap: var(--yzf-space-3);
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: var(--yzf-radius-m);
  background: var(--surface, #fff);
}
.yzf-workspace-card-copy { min-width: 0; flex: 1; }
.yzf-workspace-card-copy strong { display: block; font-size: 13px; }
.yzf-workspace-card-copy p {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 11.5px;
  line-height: 1.45;
}
.yzf-workspace-card-copy time {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 10.5px;
}
.yzf-workspace-card-actions {
  display: flex;
  flex: 0 0 auto;
  gap: var(--yzf-space-2);
}
.yzf-workspace-card-actions button { margin: 0; }
.yzf-workspace-recent {
  display: grid;
  gap: var(--yzf-space-2);
}
.yzf-workspace-recent h3 {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 12px;
  letter-spacing: .04em;
}
.yzf-workspace-empty {
  display: grid;
  justify-items: center;
  gap: var(--yzf-space-2);
  min-height: 150px;
  padding: var(--yzf-space-4);
  color: var(--muted);
  text-align: center;
  font-size: 12px;
}
.yzf-workspace-empty svg {
  width: 108px;
  height: 80px;
  fill: none;
  stroke: currentColor;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: .48;
}

/*
 * 操作引导使用原生 modal dialog 进入浏览器 Top Layer。
 * 这样即使当前页面已有帮助中心、题库 dialog 或 OCR 全屏层，说明卡与按钮仍保持最上层可点击。
 */
dialog.yzf-coach-root {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100dvh;
  max-width: none;
  max-height: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  border: 0;
  background: transparent;
  color: var(--ink);
  pointer-events: auto;
}
dialog.yzf-coach-root::backdrop { background: transparent !important; backdrop-filter: none !important; }
.yzf-coach-root[hidden] { display: none !important; }
.yzf-coach-backdrop {
  position: absolute;
  z-index: 0;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  background: transparent;
  pointer-events: auto;
}
.yzf-coach-backdrop mask { mask-type: luminance; }
.yzf-coach-shade { fill: rgba(15, 23, 42, .52); }
.yzf-coach-focus {
  position: fixed;
  z-index: 1;
  pointer-events: none;
  border: 4px solid color-mix(in srgb, var(--accent) 82%, #fff);
  border-radius: 10px;
  background: transparent;
  box-shadow:
    0 0 0 2px rgba(255,255,255,.72),
    0 10px 34px rgba(15,23,42,.28);
  transition: left .16s ease, top .16s ease, width .16s ease, height .16s ease;
}
.yzf-coach-focus[hidden] { display: none !important; }
.yzf-coach-focus.is-interactive {
  pointer-events: auto;
  cursor: pointer;
}
.yzf-coach-focus.is-interactive:hover {
  background: color-mix(in srgb, var(--accent) 16%, transparent);
}
.yzf-coach-focus.is-interactive:focus-visible {
  outline: 3px solid var(--focus-ring, #f59e0b);
  outline-offset: 3px;
}
.yzf-coach-card {
  position: fixed;
  z-index: 2;
  left: 50%;
  bottom: max(18px, env(safe-area-inset-bottom));
  width: min(460px, calc(100vw - 24px));
  transform: translateX(-50%);
  padding: 14px;
  border: 1px solid color-mix(in srgb, var(--accent) 28%, var(--border));
  border-radius: var(--yzf-radius-l);
  background: var(--surface, #fff);
  color: var(--ink);
  box-shadow: var(--yzf-dialog-shadow);
  pointer-events: auto;
}
.yzf-coach-step {
  margin-bottom: 5px;
  color: var(--accent);
  font-size: 10.5px;
  font-weight: 800;
}
.yzf-coach-card strong { display: block; font-size: 15px; }
.yzf-coach-card p {
  margin: 6px 0 12px;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.55;
}
.yzf-coach-actions {
  display: flex;
  align-items: center;
  gap: var(--yzf-space-2);
}
.yzf-coach-actions button { margin: 0; }
.yzf-coach-target { scroll-margin: 96px; }

@media (max-width: 680px) and (orientation: portrait) {
  .yzf-workspace-panel { min-height: min(700px, 89dvh); }
  .yzf-workspace-card { align-items: stretch; flex-direction: column; }
  .yzf-workspace-card-actions { justify-content: flex-end; }
  .yzf-coach-card {
    width: calc(100vw - 20px);
    max-height: min(54dvh, 430px);
    overflow: auto;
  }
}
@media (max-height: 620px) and (orientation: landscape) {
  .yzf-workspace-panel { min-height: 100%; max-height: 100%; }
  .yzf-coach-card {
    left: auto;
    right: 12px;
    bottom: 12px;
    width: min(420px, 48vw);
    max-height: calc(100dvh - 24px);
    overflow: auto;
    transform: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  .yzf-coach-focus { transition: none; }
}

/* 统一空白、加载与错误状态。 */
.yzf-state-view {
  display: grid;
  justify-items: center;
  align-content: center;
  gap: 6px;
  min-height: 170px;
  padding: var(--yzf-space-4);
  color: var(--muted);
  text-align: center;
}
.yzf-state-view.compact { min-height: 128px; padding: var(--yzf-space-3); }
.yzf-state-view svg {
  width: 104px;
  height: 76px;
  fill: none;
  stroke: currentColor;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: .44;
}
.yzf-state-view strong { color: var(--ink); font-size: 13px; }
.yzf-state-view p { max-width: 420px; margin: 0; font-size: 11.5px; line-height: 1.5; }
.yzf-state-view-symbol { display: none; }
.yzf-state-view[data-kind="empty"] .yzf-state-view-check { display: block; }
.yzf-state-view[data-kind="error"] { color: var(--delete, #dc2626); }
.yzf-state-view[data-kind="error"] .yzf-state-view-error { display: block; }
.yzf-state-view[data-kind="loading"] .yzf-state-view-loading {
  display: block;
  stroke-dasharray: 20 14;
  transform-origin: 83px 58px;
  animation: yzf-state-spin 1.1s linear infinite;
}
@keyframes yzf-state-spin { to { transform: rotate(360deg); } }

/* 近期题目的轻量盘面摘要：仅展示数字，不参与盘面交互。 */
.yzf-puzzle-preview {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  flex: 0 0 88px;
  width: 88px;
  aspect-ratio: 1;
  overflow: hidden;
  border: 2px solid color-mix(in srgb, var(--ink) 72%, var(--border));
  border-radius: 6px;
  background: var(--surface, #fff);
}
.yzf-puzzle-preview > span {
  display: grid;
  place-items: center;
  min-width: 0;
  border-right: 1px solid color-mix(in srgb, var(--border) 76%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--border) 76%, transparent);
  color: var(--accent);
  font-size: 7.5px;
  font-weight: 700;
  line-height: 1;
}
.yzf-puzzle-preview > span[data-role="given"] { color: var(--ink); font-weight: 900; }
.yzf-puzzle-preview > span:nth-child(9n) { border-right: 0; }
.yzf-puzzle-preview > span:nth-child(n+73) { border-bottom: 0; }
.yzf-puzzle-preview > span:nth-child(9n+3),
.yzf-puzzle-preview > span:nth-child(9n+6) { border-right-width: 2px; border-right-color: color-mix(in srgb, var(--ink) 56%, var(--border)); }
.yzf-puzzle-preview > span:nth-child(n+19):nth-child(-n+27),
.yzf-puzzle-preview > span:nth-child(n+46):nth-child(-n+54) { border-bottom-width: 2px; border-bottom-color: color-mix(in srgb, var(--ink) 56%, var(--border)); }

.yzf-workspace-guides {
  display: grid;
  gap: var(--yzf-space-2);
  padding-top: var(--yzf-space-2);
  border-top: 1px solid var(--border);
}
.yzf-workspace-guides > h3 {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  letter-spacing: .04em;
}
.yzf-workspace-guides > p {
  margin: -2px 0 2px;
  color: var(--muted);
  font-size: 11.5px;
  line-height: 1.45;
}
.yzf-guide-card { padding-block: 10px; }

@media (max-width: 680px) and (orientation: portrait) {
  .yzf-workspace-card.has-preview {
    display: grid;
    grid-template-columns: 88px minmax(0, 1fr);
    align-items: start;
  }
  .yzf-workspace-card.has-preview .yzf-workspace-card-actions {
    grid-column: 1 / -1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .yzf-state-view[data-kind="loading"] .yzf-state-view-loading { animation: none; }
}

/* 既有控件的语义状态：不改变主界面排版和盘面视觉。 */
button[data-yzf-variant="alert-secondary"]:not(.app-status-button):not(.app-status-back-control) {
  border-color: color-mix(in srgb, var(--delete) 38%, var(--border));
  background: color-mix(in srgb, var(--delete) 5%, var(--surface, #fff));
  color: color-mix(in srgb, var(--delete) 86%, #4b1f1c);
}
button[data-yzf-variant="alert-secondary"]:not(.app-status-button):not(.app-status-back-control):hover:not(:disabled) {
  border-color: color-mix(in srgb, var(--delete) 66%, var(--border));
  background: color-mix(in srgb, var(--delete) 10%, var(--surface, #fff));
  color: var(--delete);
}
button[data-yzf-variant="alert-secondary"]:not(.app-status-button):not(.app-status-back-control):focus-visible {
  outline-color: color-mix(in srgb, var(--delete) 28%, transparent);
  border-color: var(--delete) !important;
}

button[aria-busy="true"]:not(.app-status-button):not(.app-status-back-control) {
  position: relative;
  cursor: progress;
}
button[aria-busy="true"]:not(.app-status-button):not(.app-status-back-control)::after {
  content: "";
  position: absolute;
  top: 50%;
  right: 8px;
  width: 12px;
  height: 12px;
  margin-top: -7px;
  border: 2px solid color-mix(in srgb, currentColor 25%, transparent);
  border-top-color: currentColor;
  border-radius: 999px;
  animation: yzf-control-busy-spin .72s linear infinite;
  pointer-events: none;
}
button.action-button[aria-busy="true"]::after {
  top: 7px;
  right: 50%;
  margin: 0 -7px 0 0;
}
button.action-button[aria-busy="true"] .action-icon {
  opacity: 0;
}
@keyframes yzf-control-busy-spin { to { transform: rotate(360deg); } }

button[data-yzf-toggle="1"][aria-pressed="true"]:not(.tab-button):not(:disabled) {
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 26%, transparent),
              0 2px 7px color-mix(in srgb, var(--accent) 12%, transparent);
}

input[data-yzf-control="1"][aria-invalid="true"],
select[data-yzf-control="1"][aria-invalid="true"],
textarea[data-yzf-control="1"][aria-invalid="true"] {
  border-color: var(--delete) !important;
  background: color-mix(in srgb, var(--delete) 4%, var(--surface, #fff));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--delete) 14%, transparent);
}

summary[data-yzf-disclosure-summary="1"] {
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

[data-yzf-status-region="1"] {
  overflow-wrap: anywhere;
}

@media (prefers-reduced-motion: reduce) {
  button[aria-busy="true"]:not(.app-status-button):not(.app-status-back-control)::after {
    animation: none;
  }
  button,
  input,
  select,
  textarea,
  summary {
    transition-duration: 0.01ms !important;
  }
}

@media (forced-colors: active) {
  button[data-yzf-variant="alert-secondary"] {
    border-color: ButtonText;
  }
  button[aria-busy="true"]::after {
    border-color: GrayText;
    border-top-color: ButtonText;
  }
}


/* “帮助与现场”中心：顶部保留高频操作，低频入口集中到响应式中心。 */
.app-hub-entry {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 5px;
  min-height: 30px;
  margin: 0;
  padding: 4px 9px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-soft, #f7f9fc);
  color: #36557f;
  font-size: 12px;
  font-weight: 750;
  line-height: 1.2;
  white-space: nowrap;
}
.app-hub-entry svg {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.app-hub-entry:hover:not(:disabled),
.app-hub-entry:focus-visible {
  border-color: #9dbcf3;
  background: var(--accent-soft, #edf5ff);
  color: var(--accent-strong, #174a91);
}
.app-hub-card-badge {
  display: none;
  place-items: center;
  min-width: 17px;
  height: 17px;
  padding: 0 4px;
  border-radius: 999px;
  background: var(--accent, #2563eb);
  color: #fff;
  font-size: 9px;
  font-weight: 850;
  line-height: 1;
}
.app-hub-card-badge:not(:empty) { display: inline-grid; }

.app-hub-dialog {
  --yzf-dialog-width: 780px;
  --yzf-dialog-max-height: min(88dvh, 900px);
}
.app-hub-panel {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  max-height: min(88dvh, 900px);
}
.app-hub-header { padding-block: 14px 12px; }
.app-hub-content {
  display: grid;
  align-content: start;
  gap: 16px;
  padding: 14px 16px max(18px, env(safe-area-inset-bottom));
  overflow: auto;
  background: var(--surface-soft, #f7f9fc);
}
.app-hub-section {
  display: grid;
  gap: 8px;
}
.app-hub-section > h3 {
  margin: 0;
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.app-hub-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 9px;
}
.app-hub-card {
  position: relative;
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
  min-height: 78px;
  margin: 0;
  padding: 11px 12px;
  border: 1px solid var(--border);
  border-radius: 13px;
  background: var(--surface, #fff);
  color: var(--ink);
  text-align: left;
  text-decoration: none;
  box-shadow: 0 3px 12px rgba(15, 23, 42, .05);
}
.app-hub-card:hover,
.app-hub-card:focus-visible {
  border-color: color-mix(in srgb, var(--accent) 46%, var(--border));
  background: color-mix(in srgb, var(--accent) 4%, var(--surface, #fff));
  color: var(--ink);
  outline: none;
  box-shadow: 0 7px 20px rgba(37, 99, 235, .10);
}
.app-hub-card-primary {
  border-color: color-mix(in srgb, var(--accent) 30%, var(--border));
  background: color-mix(in srgb, var(--accent) 4%, var(--surface, #fff));
}
.app-hub-card-icon {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 11px;
  background: var(--accent-soft, #edf5ff);
  color: var(--accent-strong, #174a91);
}
.app-hub-card-icon svg {
  width: 22px;
  height: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.app-hub-card-copy { min-width: 0; }
.app-hub-card-copy strong {
  display: block;
  color: var(--ink);
  font-size: 13px;
  font-weight: 800;
  line-height: 1.25;
}
.app-hub-card-copy small {
  display: block;
  margin-top: 3px;
  color: var(--muted);
  font-size: 11px;
  line-height: 1.4;
}
.app-hub-language-card { cursor: default; }
.app-hub-language-card:hover,
.app-hub-language-switch,
.app-hub-appearance-switch {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  padding: 2px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-soft, #f7f9fc);
}
:is(.app-hub-language-switch, .app-hub-appearance-switch) button {
  min-height: 30px;
  margin: 0;
  padding: 4px 8px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--muted);
  font-size: 11px;
  font-weight: 750;
}
:is(.app-hub-language-switch, .app-hub-appearance-switch) button[aria-pressed="true"] {
  background: var(--surface, #fff);
  color: var(--accent-strong, #174a91);
  box-shadow: 0 2px 7px rgba(15, 23, 42, .10);
}

@media (max-width: 900px) {
  .topbar-language { display: none !important; }
}
@media (max-width: 680px) and (orientation: portrait) {
  .app-hub-dialog {
    min-height: min(720px, 91dvh);
  }
  .app-hub-panel { min-height: min(720px, 91dvh); max-height: 91dvh; }
  .app-hub-grid { grid-template-columns: 1fr; }
  .app-hub-card { min-height: 70px; }
  .app-hub-entry .action-label { display: none; }
  .app-hub-entry { width: 32px; min-width: 32px; padding-inline: 6px; }
}
@media (max-height: 620px) and (orientation: landscape) {
  .app-hub-panel { min-height: 100%; max-height: 100%; }
  .app-hub-content { gap: 10px; padding: 10px; }
  .app-hub-grid { grid-template-columns: 1fr; gap: 6px; }
  .app-hub-card { min-height: 62px; padding-block: 8px; }
  .app-hub-entry .action-label { display: none; }
  .app-hub-entry { width: 30px; min-width: 30px; padding-inline: 5px; }
}

@media (forced-colors: active) {
  .app-hub-card,
  .app-hub-entry,
  .app-hub-language-switch { border-color: ButtonText; }
}

/*
 * 正式外观主题。
 * 主题只改变界面语义色和基础盘面底色；技巧本身的彩色编码保持原始含义，
 * 避免深色模式把删数、强弱链、Truth/Link 或手工标记映射成另一套逻辑。
 */
.app-hub-appearance-card {
  grid-column: 1 / -1;
  cursor: default;
}
.app-hub-appearance-switch {
  flex-wrap: wrap;
  justify-content: flex-end;
}

:root[data-yzf-theme="dark"],
:root[data-yzf-theme="system"][data-yzf-resolved-theme="dark"] {
  --bg: #0b1220;
  --surface: #121c2d;
  --surface-soft: #172235;
  --surface-muted: #1d2a40;
  --panel: #172235;
  --border: #33445f;
  --border-strong: #526784;
  --muted: #a7b4c7;
  --ink: #edf3fb;
  --accent: #6ea8ff;
  --accent-strong: #9dc1ff;
  --accent-soft: #203a62;
  --accent-faint: #162b4c;
  --place: #5ee0aa;
  --delete: #ff8585;
  --yzf-backdrop: rgba(2, 6, 23, .72);
  --yzf-dialog-shadow: 0 28px 90px rgba(0, 0, 0, .58);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, .34);
  --shadow-md: 0 14px 36px rgba(0, 0, 0, .38);
  --board-cell-bg: #111827;
  --board-grid: #526174;
  --board-grid-strong: #d8e1ee;
  --board-candidate: #d4deeb;
  --board-given: #f8fafc;
  --board-solved: #79b8ff;
  --board-selected: #193d6c;
  --board-peer: #182438;
}

:root[data-yzf-theme="contrast"] {
  --bg: #ffffff;
  --surface: #ffffff;
  --surface-soft: #ffffff;
  --surface-muted: #f1f1f1;
  --panel: #ffffff;
  --border: #000000;
  --border-strong: #000000;
  --muted: #292929;
  --ink: #000000;
  --accent: #0037c5;
  --accent-strong: #001f7a;
  --accent-soft: #dce7ff;
  --accent-faint: #edf2ff;
  --place: #006b3c;
  --delete: #a60000;
  --yzf-backdrop: rgba(0, 0, 0, .72);
  --yzf-dialog-shadow: none;
  --shadow-sm: none;
  --shadow-md: none;
  --shadow-board: none;
  --board-cell-bg: #ffffff;
  --board-grid: #000000;
  --board-grid-strong: #000000;
  --board-candidate: #000000;
  --board-given: #000000;
  --board-solved: #0037c5;
  --board-selected: #dce7ff;
  --board-peer: #f3f3f3;
}

html[data-yzf-theme="dark"],
html[data-yzf-theme="system"][data-yzf-resolved-theme="dark"],
html[data-yzf-theme="dark"] body,
html[data-yzf-theme="system"][data-yzf-resolved-theme="dark"] body {
  background-color: #0b1220;
}

html[data-yzf-theme="dark"] body,
html[data-yzf-theme="system"][data-yzf-resolved-theme="dark"] body {
  background:
    radial-gradient(circle at 15% 10%, rgba(59, 130, 246, .13), transparent 32rem),
    linear-gradient(145deg, #101a2b 0%, var(--bg) 56%, #080e19 100%);
}

html[data-yzf-theme="contrast"],
html[data-yzf-theme="contrast"] body {
  background: #ffffff;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .topbar, .tab-shell, .card, .technique-toolbar, .numpad, .input-panel,
  .tlg-solver-panel, .manual-marks-panel, #tabControls > details,
  .yzf-panel-header, .yzf-panel-actions, .yzf-task-row, .yzf-workspace-card,
  .app-hub-card, .app-hub-language-switch, .app-hub-appearance-switch
) {
  background: var(--surface);
  color: var(--ink);
  border-color: var(--border);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .yzf-diagnostics-dialog, .yzf-task-center-dialog, .yzf-workspace-dialog,
  .app-hub-dialog, dialog[data-yzf-panel="1"]
) {
  background: var(--surface);
  color: var(--ink);
  border-color: var(--border-strong);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .yzf-diagnostics-summary, .yzf-diagnostics-output, .yzf-task-list,
  .yzf-workspace-content, .app-hub-content, .tab-list, .hint-panel,
  #tabControls > .generate-options, .training-text-filter-dialog .dialog-body
) {
  background: var(--surface-soft) !important;
  color: var(--ink);
  border-color: var(--border);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) button {
  border-color: var(--border);
  color: var(--ink);
}

/*
 * 主页面旧样式中有若干带 ID 的白色表单规则。主题层必须明确覆盖这些
 * 高特异性声明，否则深色模式会出现白底白字的下拉框。这里仅覆盖表单，
 * 不使用全局 button !important，避免破坏品牌、警示与状态按钮语义。
 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  select, textarea, input[type="text"], input[type="number"], input[type="search"], input[type="url"], input[type="email"]
) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  select, textarea, input[type="text"], input[type="number"], input[type="search"], input[type="url"], input[type="email"]
)::placeholder {
  color: var(--muted);
  opacity: 1;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) option {
  background: var(--surface);
  color: var(--ink);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
button:hover:not(:disabled) {
  border-color: color-mix(in srgb, var(--accent) 58%, var(--border));
  background: var(--accent-faint);
  color: var(--accent-strong);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
button.primary {
  border-color: #6ea8ff;
  background: linear-gradient(180deg, #3978d3, #285ca8);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(0, 0, 0, .34);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.brand-title, .app-hub-card-copy strong, .yzf-workspace-card strong, .yzf-panel-header strong) {
  color: var(--ink);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.global-actions .action-button, .global-actions .action-button.primary, .numpad button) {
  background: var(--surface-soft);
  color: #dce7f5;
  border-color: var(--border);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.global-actions .action-button:is(#btnSolve, #btnStep, #btnApply) {
  border-color: #365f98;
  background: #162c4b;
  color: #9dc1ff;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.global-actions .action-button:is(#btnGenerate, #btnLoad) {
  border-color: #28614f;
  background: #153329;
  color: #7ee6ba;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tab-button {
  color: #b3c0d2;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tab-button:hover:not(.active) {
  background: #25324a;
  color: #edf3fb;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tab-button.active {
  border-color: #4976b5;
  background: #20304a;
  color: #a8c9ff;
  box-shadow: 0 2px 8px rgba(0, 0, 0, .3);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(#tabControls > details > summary, .tlg-solver-panel > summary, .manual-marks-panel > summary, .input-panel > summary) {
  background: var(--surface-soft);
  color: #d7e2f1;
  border-color: var(--border);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.hint-panel {
  border-color: #345f96 !important;
  background: linear-gradient(135deg, #15283f, #172c49) !important;
  color: #c8d8ec;
}

/* 深色界面下，盘面使用独立的高对比分析画布；技巧彩色标记仍沿用原有语义色。 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-board {
  border-color: var(--board-grid-strong);
  background: var(--board-grid-strong);
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell {
  border-color: var(--board-grid);
  background: var(--board-cell-bg);
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell:is(.box-left, .box-top, .box-right, .box-bottom) {
  border-color: var(--board-grid-strong);
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell.selected {
  background: var(--board-selected);
  box-shadow: inset 0 0 0 3px var(--accent);
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell.hint-peer { background: var(--board-peer); }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell.hint-structure,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.sudoku-cell.hint-eliminate { background: var(--board-cell-bg); }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.cell-value.given { color: var(--board-given); }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.cell-value.solved { color: var(--board-solved); }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"])
.candidate-grid { color: var(--board-candidate); }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.sudoku-cell.manual-cell-color {
  background: color-mix(in srgb, var(--manual-cell-bg, #fff8a6) 36%, var(--board-cell-bg)) !important;
}

/* 高对比模式减少装饰，把信息差异集中到边框、文字和形状。 */
:root[data-yzf-theme="contrast"] * {
  text-shadow: none !important;
}
:root[data-yzf-theme="contrast"] :is(.topbar, .tab-shell, .card, dialog, .app-hub-card, .yzf-workspace-card) {
  box-shadow: none !important;
  backdrop-filter: none !important;
}
:root[data-yzf-theme="contrast"] :is(button, select, textarea, input, summary, .app-hub-card) {
  border-width: 2px;
}
:root[data-yzf-theme="contrast"] button:focus-visible,
:root[data-yzf-theme="contrast"] select:focus-visible,
:root[data-yzf-theme="contrast"] input:focus-visible,
:root[data-yzf-theme="contrast"] textarea:focus-visible,
:root[data-yzf-theme="contrast"] a:focus-visible {
  outline: 4px solid #000000;
  outline-offset: 3px;
}

@media (max-width: 680px) {
  .app-hub-appearance-switch {
    grid-column: 1 / -1;
    width: 100%;
    justify-content: stretch;
  }
  .app-hub-appearance-switch button { flex: 1 1 auto; }
}

@media (forced-colors: active) {
  .app-hub-appearance-switch { border-color: ButtonText; }
}

/* 主题下的禁用控件不能退回浏览器默认白底，否则会被误认为可点击。 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(button, select, textarea, input):disabled {
  border-color: var(--border) !important;
  background: var(--surface-muted) !important;
  color: var(--muted) !important;
  opacity: .62;
  box-shadow: none !important;
}
:root[data-yzf-theme="contrast"] :is(button, select, textarea, input):disabled {
  border-color: #555 !important;
  background: #efefef !important;
  color: #444 !important;
  opacity: 1;
  text-decoration: line-through;
  text-decoration-thickness: 1px;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) {
  scrollbar-color: #526784 #121c2d;
}

/* 高对比主题以黑白边界为主，品牌色只承担文字/主按钮强调。 */
:root[data-yzf-theme="contrast"] button:not(:disabled) {
  border-color: #000000 !important;
  background: #ffffff !important;
  color: #000000 !important;
  box-shadow: none !important;
}
:root[data-yzf-theme="contrast"] :is(
  button.primary,
  button[data-yzf-variant="brand-primary"],
  .mobile-primary
):not(:disabled) {
  border-color: #000000 !important;
  background: #0037c5 !important;
  color: #ffffff !important;
}
:root[data-yzf-theme="contrast"] button[data-yzf-variant="brand-secondary"]:not(:disabled) {
  border-color: #000000 !important;
  background: #ffffff !important;
  color: #0037c5 !important;
}
:root[data-yzf-theme="contrast"] button[data-yzf-variant^="alert-"]:not(:disabled) {
  border-color: #a60000 !important;
  background: #ffffff !important;
  color: #a60000 !important;
}
:root[data-yzf-theme="contrast"] button[aria-pressed="true"]:not(:disabled),
:root[data-yzf-theme="contrast"] .tab-button.active {
  outline: 3px solid #000000;
  outline-offset: -5px;
}

/* 深色主题下，业务面板按钮不得回退到旧版白底。 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .manual-marks-panel, .tlg-solver-panel, .input-panel, #tabControls,
  .tlg-library-dialog, .training-text-filter-dialog
) button:not(:disabled):not(.primary):not([data-yzf-variant="brand-primary"]) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
  box-shadow: none;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
button[data-yzf-variant="alert-secondary"]:not(:disabled) {
  border-color: #86454b !important;
  background: #352027 !important;
  color: #ffaaaa !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
button[data-yzf-variant="brand-primary"]:not(:disabled),
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
button.primary:not(:disabled) {
  border-color: #6ea8ff !important;
  background: linear-gradient(180deg, #3978d3, #285ca8) !important;
  color: #ffffff !important;
}

/* TLG 的状态、结果与结构标签也属于分析画布，不能在深色主题中残留白色卡片。 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .tlg-solver-state-panel, .tlg-solver-solution-panel,
  .tlg-library-share-panel, .tlg-library-list-panel, .tlg-library-editor
) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.tlg-solver-state-title, .tlg-solver-state-group-title, .tlg-solver-solution-title) {
  color: #a8c9ff !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tlg-solver-chip {
  border-color: #5579aa !important;
  background: #203653 !important;
  color: #e3edf9 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tlg-solver-chip button:not(:disabled) {
  border: 0 !important;
  background: transparent !important;
  color: #ffaaaa !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.tlg-solver-status, .tlg-library-status) {
  border-color: #4f78aa !important;
  background: #172b46 !important;
  color: #d6e5f7 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.tlg-solver-status, .tlg-library-status)[data-tone="ok"] {
  border-color: #3c9a73 !important;
  background: #14352a !important;
  color: #9ff0cb !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
:is(.tlg-solver-status, .tlg-library-status)[data-tone="error"] {
  border-color: #c75b63 !important;
  background: #3a2027 !important;
  color: #ffb3b8 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.tlg-solver-solution {
  color: #dbe8f6 !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.manual-mark-color-row input[type="color"] {
  color-scheme: dark;
  border-color: var(--border) !important;
  background: var(--surface-muted) !important;
}

/* 深色/高对比主题：技巧配置表必须完整继承主题语义色。 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .technique-memory-row,
  .technique-toolbar,
  .technique-row td
) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .technique-table th,
  .technique-memory-control,
  .technique-option-check,
  .technique-name-cell,
  .technique-name-cell span,
  .technique-score-cell,
  .technique-suboption
) {
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .technique-table th,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .technique-suboption {
  color: var(--muted) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .technique-row:hover td {
  border-color: color-mix(in srgb, var(--accent) 52%, var(--border)) !important;
  background: var(--accent-faint) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .technique-row.disabled {
  color: var(--muted) !important;
  opacity: .78;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"], [data-yzf-theme="contrast"]) :is(
  .technique-name-cell input[type="checkbox"],
  .technique-option-check input[type="checkbox"],
  .technique-suboption input[type="checkbox"]
) {
  accent-color: var(--accent);
}

/*
 * V512 dark-theme exhaustive UI contrast closure.
 * Legacy rules in index.html still assign light backgrounds to several controls.
 * Keep the override scoped to dark/system-dark so light and high-contrast themes
 * retain their established semantics.
 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  #tabTechniques .technique-toolbar button:not(:disabled):not(.primary),
  .ocr-import-actions button:not(:disabled):not(.primary),
  .ocr-import-actions select:not(:disabled),
  .ocr-file-button,
  .ocr-toggle-chip
) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
  box-shadow: none !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  #tabTechniques .technique-toolbar button:not(:disabled):not(.primary),
  .ocr-import-actions button:not(:disabled):not(.primary),
  .ocr-file-button,
  .ocr-toggle-chip
):hover,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  #tabTechniques .technique-toolbar button:not(:disabled):not(.primary),
  .ocr-import-actions button:not(:disabled):not(.primary),
  .ocr-file-button,
  .ocr-toggle-chip
):focus-visible,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .ocr-toggle-chip:focus-within {
  border-color: var(--accent) !important;
  background: var(--accent-faint) !important;
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .all-steps-filter {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .all-steps-filter label,
  .all-steps-filter-status,
  .tlg-solver-grid,
  .tlg-solver-grid label,
  .tlg-solver-grid label > span
) {
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .all-steps-filter-status,
  .batch-status,
  .tlg-solver-status
) {
  color: var(--muted) !important;
}

/* Dynamic dialogs and secondary surfaces created by ui-foundation/app.js. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .app-hub-dialog,
  .yzf-diagnostics-dialog,
  .yzf-workspace-dialog,
  .yzf-task-center-dialog,
  .training-text-filter-dialog,
  .tlg-library-dialog,
  .step-explain-dialog
) button:not(:disabled):not(.primary):not([data-yzf-variant="brand-primary"]):not([data-yzf-variant^="alert-"]):not(.app-status-button):not(.app-status-back-control) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
  box-shadow: none !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .app-hub-dialog,
  .yzf-diagnostics-dialog,
  .yzf-workspace-dialog,
  .yzf-task-center-dialog,
  .training-text-filter-dialog,
  .tlg-library-dialog,
  .step-explain-dialog
) button:not(:disabled):not(.primary):not([data-yzf-variant="brand-primary"]):not([data-yzf-variant^="alert-"]):not(.app-status-button):not(.app-status-back-control):hover,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .app-hub-dialog,
  .yzf-diagnostics-dialog,
  .yzf-workspace-dialog,
  .yzf-task-center-dialog,
  .training-text-filter-dialog,
  .tlg-library-dialog,
  .step-explain-dialog
) button:not(:disabled):not(.primary):not([data-yzf-variant="brand-primary"]):not([data-yzf-variant^="alert-"]):not(.app-status-button):not(.app-status-back-control):focus-visible {
  border-color: var(--accent) !important;
  background: var(--accent-faint) !important;
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .training-text-filter-field,
  .training-text-filter-field > span,
  .training-text-filter-case,
  .training-text-filter-case > span,
  .tlg-library-filebar label,
  .tlg-library-filebar label > span,
  .tlg-library-share-panel label,
  .tlg-library-share-panel label > span,
  .tlg-library-editor label,
  .tlg-library-editor label > span
) {
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .tlg-library-count,
  .tlg-library-empty,
  .tlg-library-summary,
  .tlg-library-share-summary
) {
  color: var(--muted) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-entry {
  border-color: var(--border-strong) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-entry:hover,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-entry:focus-visible {
  border-color: var(--accent) !important;
  background: var(--accent-faint) !important;
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tlg-library-summary {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--muted) !important;
}

/* TLG library secondary/selected states. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .tlg-library-share-summary,
  .tlg-library-table th,
  .tlg-library-table td
) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tlg-library-row:hover td {
  background: var(--surface-muted) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tlg-library-row[aria-selected="true"] td {
  background: var(--accent-faint) !important;
  color: var(--ink) !important;
}

/* Step explanation cards and details must not retain translucent white layers. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .step-explain-panel .step-explain-section,
  .step-explain-dialog-content .step-explain-section,
  .step-explain-details,
  .step-explain-pill
) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .step-explain-panel .step-explain-section-heading,
  .step-explain-dialog-content .step-explain-section-heading,
  .step-explain-details > summary
) {
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .step-explain-section-math {
  background: color-mix(in srgb, var(--surface-soft) 84%, #0f766e 16%) !important;
}

/* Dedicated mobile solve mode: close the complete light-only legacy surface set. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) body.mobile-solve-mode,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell {
  background: linear-gradient(180deg, #101a2b, var(--bg)) !important;
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-topbar,
  .mobile-solve-status,
  .mobile-solve-drawer,
  .mobile-solve-new-puzzle-panel,
  .mobile-solve-shell .manual-marks-panel.mobile-manual-marks
) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
  box-shadow: var(--shadow-md) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-title,
  .mobile-solve-drawer-title,
  .mobile-solve-new-puzzle-header strong,
  .mobile-solve-new-puzzle-fieldset legend,
  .mobile-solve-setting-row,
  .mobile-solve-language-row,
  .mobile-solve-new-puzzle-options label,
  .mobile-solve-new-puzzle-options b
) {
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-input-state,
  .mobile-solve-setting-copy small,
  .mobile-solve-new-puzzle-hint,
  .mobile-solve-new-puzzle-options small
) {
  color: var(--muted) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-topbar > button:not(.app-status-button):not(.app-status-back-control),
  .mobile-solve-actions button:not(.mobile-primary),
  .mobile-solve-drawer button,
  .mobile-solve-new-puzzle-header button,
  .mobile-solve-new-puzzle-actions button:not(.mobile-primary),
  .mobile-solve-shell .manual-marks-panel.mobile-manual-marks button
) {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
  box-shadow: none !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-topbar .app-status-back-control {
  border-color: var(--border-strong) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-actions #btnMobileSolveHint,
  .mobile-solve-actions #btnMobileSolveApply,
  .mobile-solve-actions #btnMobileSolveInputMode[aria-pressed="true"],
  .mobile-solve-actions button[data-mark-active="true"],
  .mobile-solve-drawer-grid button[aria-pressed="true"],
  .mobile-solve-new-puzzle-options label:has(input:checked)
) {
  border-color: var(--accent) !important;
  background: var(--accent-faint) !important;
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .mobile-solve-actions button.mobile-primary,
  .mobile-solve-new-puzzle-actions .mobile-primary
) {
  border-color: #6ea8ff !important;
  background: linear-gradient(180deg, #3978d3, #285ca8) !important;
  color: #fff !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .numpad button[data-digit] {
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .numpad button[data-digit].active {
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-new-puzzle-options label {
  border-color: var(--border) !important;
  background: var(--surface-soft) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-new-puzzle-warning {
  border-color: #a56d2a !important;
  background: #362711 !important;
  color: #ffd28a !important;
}

/* TLG library chrome: avoid light title/share bars inside an otherwise dark dialog. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  .tlg-library-header,
  .tlg-library-toolbar,
  .tlg-library-filebar,
  .tlg-library-sharebar
) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tlg-library-header strong {
  color: var(--ink) !important;
}

/* Global transient status belongs to the selected theme as well. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .app-status-toast {
  border-color: color-mix(in srgb, var(--toast-color, var(--accent)) 58%, var(--border)) !important;
  background: var(--surface-muted) !important;
  color: var(--ink) !important;
  box-shadow: var(--shadow-md) !important;
}

/* V513: dark Sudoku canvas line hierarchy.
 * V456 moved all grid drawing into board-wrap custom properties and the
 * sudoku-board pseudo-element. The older dark-theme rules only recolored
 * cell borders, which are disabled by the V456 geometry, so the live board
 * kept the light-theme #646464 normal lines and black box separators.
 * Use a quiet blue-gray minor grid and a clearly brighter (not white) major
 * grid so 3x3 boxes remain readable without cutting the dark board into nine
 * harsh black blocks. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(.board-wrap, .sudoku-board) {
  --yzf-grid-line-color: #39485d;
  --yzf-box-line-color: #8193ad;
}

/* Keep selected/peer states visually subordinate to the fixed grid. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell.selected {
  background: #1d416d;
  box-shadow: inset 0 0 0 3px #76adff;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell.hint-peer {
  background: #18263a;
}

/* The high-contrast theme must not inherit the decorative dark palette. */
:root[data-yzf-theme="contrast"] :is(.board-wrap, .sudoku-board) {
  --yzf-grid-line-color: #000000;
  --yzf-box-line-color: #000000;
}

/* Preserve board-state meaning on the dark analysis canvas. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell.hint-place {
  background: #17382f;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell:is(
  .mobile-same-digit,
  .mobile-same-digit-candidate,
  .mobile-same-digit-value
) {
  background: #382b14 !important;
  box-shadow: inset 0 0 0 2px #d59a2c;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell.mobile-same-digit-value .cell-value {
  color: #ffd58a;
  text-shadow: none;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell:is(
  .mobile-same-digit.selected,
  .mobile-same-digit-candidate.selected,
  .mobile-same-digit-value.selected
) {
  background: #1d416d !important;
  box-shadow: inset 0 0 0 3px #76adff;
}

/* Whole-cell solver highlights keep their original semantic colors. Most are
 * deliberately light, so dark-theme foreground inheritance must be reversed
 * locally or the digits become pale-on-pastel. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell.solver-cell-role-fill :is(
  .candidate-grid,
  .cell-value.given,
  .cell-value.solved,
  .cell-value.suggested
) {
  color: #111827 !important;
  text-shadow: none !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell:is(
  .solver-cell-bkclr-1, .solver-cell-bkclr-2, .solver-cell-bkclr-3,
  .solver-cell-bkclr-4, .solver-cell-bkclr-5, .solver-cell-bkclr-6,
  .solver-cell-bkclr-7, .solver-cell-bkclr-8, .solver-cell-bkclr-9,
  .solver-cell-bkclr-10, .solver-cell-bkclr-11
) .candidate-grid {
  color: #111827 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell:is(
  .solver-cell-bkclr-1, .solver-cell-bkclr-2, .solver-cell-bkclr-3,
  .solver-cell-bkclr-4, .solver-cell-bkclr-5, .solver-cell-bkclr-6,
  .solver-cell-bkclr-7, .solver-cell-bkclr-8, .solver-cell-bkclr-9,
  .solver-cell-bkclr-10, .solver-cell-bkclr-11
) .cell-value.given {
  color: #111827 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell:is(
  .solver-cell-bkclr-1, .solver-cell-bkclr-2, .solver-cell-bkclr-3,
  .solver-cell-bkclr-4, .solver-cell-bkclr-5, .solver-cell-bkclr-6,
  .solver-cell-bkclr-7, .solver-cell-bkclr-8, .solver-cell-bkclr-9,
  .solver-cell-bkclr-10, .solver-cell-bkclr-11
) .cell-value.solved {
  color: #0b356a !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell:is(
  .solver-cell-bkclr-1, .solver-cell-bkclr-2, .solver-cell-bkclr-3,
  .solver-cell-bkclr-4, .solver-cell-bkclr-5, .solver-cell-bkclr-6,
  .solver-cell-bkclr-7, .solver-cell-bkclr-8, .solver-cell-bkclr-9,
  .solver-cell-bkclr-10, .solver-cell-bkclr-11
) .cell-value.suggested {
  color: #0b3d2e !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .sudoku-cell.solver-cell-bkclr-12 :is(
  .candidate-grid,
  .cell-value.given,
  .cell-value.solved,
  .cell-value.suggested
) {
  color: #ffffff !important;
  text-shadow: none !important;
}

/* The twelfth candidate background is the sole dark fill in the legacy
 * palette; it also needs a light glyph in every theme. */
.candidate.bkclr-12 {
  color: #ffffff !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell.mobile-same-digit-value.selected .cell-value.given {
  color: var(--board-given) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell.mobile-same-digit-value.selected .cell-value.solved {
  color: var(--board-solved) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .mobile-solve-shell .sudoku-cell.mobile-same-digit-value.selected .cell-value.suggested {
  color: var(--place) !important;
}


/*
 * V512 full-chain dark-theme closure.
 * Covers real solve-path/all-steps trees, native file controls and the remaining
 * legacy light surfaces that only appear after a complete solve or file workflow.
 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(
  #tree > .json-treeview,
  #allStepsTree > .json-treeview,
  .json-treeview
) {
  border-color: var(--border-strong) !important;
  background: var(--surface-soft) !important;
  color: var(--ink) !important;
  scrollbar-color: var(--border-strong) var(--surface-soft);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .json-treeview ul ul::before {
  border-left-color: #536783 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .json-treeview li::before {
  border-top-color: #536783 !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row {
  color: var(--ink) !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row:not(.step-row):hover,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row:not(.step-row).selected {
  background: var(--accent-faint) !important;
  outline-color: #577baa !important;
}

/* Preserve the five difficulty levels, but replace retina-searing light fills. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-difficulty-1 {
  --yzf-step-row-bg: #182438;
  --yzf-step-row-fg: #e7eef8;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-difficulty-2 {
  --yzf-step-row-bg: #183d2c;
  --yzf-step-row-fg: #dbf7e7;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-difficulty-3 {
  --yzf-step-row-bg: #4a421d;
  --yzf-step-row-fg: #fff2b3;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-difficulty-4 {
  --yzf-step-row-bg: #56331f;
  --yzf-step-row-fg: #ffe0c2;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-difficulty-5 {
  --yzf-step-row-bg: #57272f;
  --yzf-step-row-fg: #ffdce0;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-row {
  background: var(--yzf-step-row-bg, #182438) !important;
  color: var(--yzf-step-row-fg, var(--ink)) !important;
  outline-color: transparent;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-row :is(
  .tree-key, .tree-colon, .tree-value, .tree-type,
  .tree-value.string, .tree-value.number, .tree-value.boolean,
  .tree-value.null, .tree-value.collection
) {
  color: inherit !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-row:hover {
  filter: brightness(1.13) !important;
  outline: 1px solid #7c91ad !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-row.step-row.selected {
  filter: none !important;
  outline: 3px solid #79b8ff !important;
  box-shadow: inset 6px 0 0 #79b8ff, 0 0 0 2px #0d1726 !important;
  color: #ffffff !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-toggle {
  border-color: #607694 !important;
  background: #111c2d !important;
  color: #dce7f5 !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-toggle:not(.empty):hover,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-toggle:not(.empty):focus-visible {
  border-color: #79b8ff !important;
  background: #203a5d !important;
  color: #ffffff !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-toggle.empty {
  border-color: transparent !important;
  background: transparent !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-key { color: #9bc7ff !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-colon,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-type { color: var(--muted) !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value { color: #e7eef8 !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value.string { color: #ffc58f !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value.number { color: #8ed8ff !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value.boolean { color: #d9b4ff !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value.null { color: #ffb0b8 !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .tree-value.collection { color: #b9c8dc !important; }

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .branch-panel {
  border-color: #426a9d !important;
  background: #172a43 !important;
  color: #e6f0ff !important;
  box-shadow: none !important;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .branch-panel-delta.better { color: #74e2b5 !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .branch-panel-delta.worse { color: #ffc078 !important; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) :is(.branch-panel-delta.neutral, .branch-panel-change) { color: #bdcbe0 !important; }

/* Native file controls are used by batch solving; hidden OCR/TLG inputs inherit safely. */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) input[type="file"]:not(.ocr-native-file-input) {
  border-color: var(--border) !important;
  background: var(--surface) !important;
  color: var(--ink) !important;
  color-scheme: dark;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) input[type="file"]:not(.ocr-native-file-input)::file-selector-button {
  height: 100%;
  margin: -4px 8px -4px -7px;
  padding: 4px 10px;
  border: 0;
  border-right: 1px solid var(--border);
  background: #203653;
  color: #edf3fb;
  cursor: pointer;
  font: inherit;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) input[type="file"]:not(.ocr-native-file-input):hover::file-selector-button,
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) input[type="file"]:not(.ocr-native-file-input):focus-visible::file-selector-button {
  background: #2b568b;
  color: #ffffff;
}
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .batch-grid label {
  color: var(--ink) !important;
}

/*
 * V512 深色全链路补漏：功能导引（Coach Marks）位于浏览器 Top Layer，
 * 不能依赖普通业务面板的按钮/卡片覆盖规则。此前说明卡本身继承了深色变量，
 * 但“跳过”按钮仍命中 index.html 的白底按钮规则，高亮框还保留白色外圈，
 * 形成白底浅字与过亮边缘。这里直接为整套导引语义层定义深色外观。
 */
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
dialog.yzf-coach-root {
  color-scheme: dark;
  background: transparent !important;
  border-color: transparent !important;
  box-shadow: none !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-backdrop {
  background: transparent;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-shade {
  fill: rgba(2, 6, 23, .74);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-focus {
  border-color: #79afff;
  background: transparent;
  box-shadow:
    0 0 0 2px rgba(8, 14, 26, .96),
    0 0 0 5px rgba(110, 168, 255, .22),
    0 14px 42px rgba(0, 0, 0, .52);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-focus.is-interactive:hover {
  background: color-mix(in srgb, var(--accent) 24%, transparent);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-card {
  border-color: color-mix(in srgb, var(--accent) 38%, var(--border-strong));
  background-color: var(--surface);
  background-image:
    linear-gradient(180deg,
      color-mix(in srgb, var(--surface-soft) 90%, var(--accent-faint)) 0%,
      var(--surface) 100%);
  color: var(--ink);
  box-shadow:
    0 28px 90px rgba(0, 0, 0, .62),
    0 0 0 1px rgba(255, 255, 255, .025) inset;
  scrollbar-color: var(--border-strong) var(--surface);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-step {
  color: var(--accent-strong);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-card strong {
  color: var(--ink);
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-card p {
  color: #becbdd;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-actions button:not(.primary):not(:disabled) {
  border-color: var(--border-strong) !important;
  background: var(--surface-muted) !important;
  color: var(--ink) !important;
  box-shadow: none !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-actions button:not(.primary):hover:not(:disabled) {
  border-color: var(--accent) !important;
  background: var(--accent-faint) !important;
  color: var(--accent-strong) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
.yzf-coach-actions button:focus-visible {
  outline: 3px solid var(--focus-ring, #f5b942);
  outline-offset: 2px;
}

/* 高对比模式继续使用明确的黑白语义，不继承深色渐变。 */
:root[data-yzf-theme="contrast"] .yzf-coach-backdrop {
  background: transparent;
}
:root[data-yzf-theme="contrast"] .yzf-coach-shade {
  fill: rgba(0, 0, 0, .76);
}
:root[data-yzf-theme="contrast"] .yzf-coach-focus {
  border-color: #ffffff;
  background: transparent;
  box-shadow: 0 0 0 3px #000000;
}
:root[data-yzf-theme="contrast"] .yzf-coach-card {
  border: 3px solid #000000;
  background: #ffffff;
  color: #000000;
  box-shadow: none;
}
:root[data-yzf-theme="contrast"] .yzf-coach-card :is(.yzf-coach-step, strong, p) {
  color: #000000;
}
:root[data-yzf-theme="contrast"] .yzf-coach-actions button:not(.primary):not(:disabled) {
  border-color: #000000 !important;
  background: #ffffff !important;
  color: #000000 !important;
}

/* YZF Sudoku copyright and contact notice. */
html[lang^="zh"] .yzf-lang-en,
html[lang="en"] .yzf-lang-zh { display: none !important; }
.yzf-copyright-card {
  padding: 15px 17px;
  border: 1px solid var(--border);
  border-radius: var(--yzf-radius-m);
  background: var(--surface-soft);
  color: var(--ink);
  box-shadow: 0 6px 18px rgba(15, 23, 42, .08);
  font-size: 13px;
  line-height: 1.62;
}
.yzf-copyright-card p { margin: 0 0 9px; }
.yzf-copyright-card p:last-child { margin-bottom: 0; }
.yzf-copyright-card a { color: var(--accent-strong); font-weight: 700; overflow-wrap: anywhere; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"]) .yzf-copyright-card {
  border-color: var(--border);
  background: var(--surface-soft);
  color: var(--ink);
  box-shadow: 0 8px 22px rgba(0, 0, 0, .24);
}
:root[data-yzf-theme="contrast"] .yzf-copyright-card {
  border: 2px solid ButtonText;
  background: Canvas;
  color: CanvasText;
  box-shadow: none;
}
:root[data-yzf-theme="contrast"] .yzf-copyright-card a { color: LinkText; }


/*
 * V520 技巧配置等级底色恢复。
 * 选择器严格限制在 #techniqueList，避免影响步骤树、训练下拉框、提示高亮及共用技巧配色。
 */
#techniqueList .technique-row[data-technique-level="1"] { --yzf-technique-config-bg: rgb(255, 255, 255); }
#techniqueList .technique-row[data-technique-level="2"] { --yzf-technique-config-bg: rgb(100, 255, 100); }
#techniqueList .technique-row[data-technique-level="3"] { --yzf-technique-config-bg: rgb(255, 255, 100); }
#techniqueList .technique-row[data-technique-level="4"] { --yzf-technique-config-bg: rgb(255, 150, 80); }
#techniqueList .technique-row[data-technique-level="5"] { --yzf-technique-config-bg: rgb(255, 100, 100); }

#techniqueList .technique-row[data-technique-level] > td,
#techniqueList .technique-row[data-technique-level]:hover > td {
  background: var(--yzf-technique-config-bg) !important;
}

#techniqueList .technique-row[data-technique-level]:hover > td {
  border-color: color-mix(in srgb, var(--accent) 58%, var(--border)) !important;
}

:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
  #techniqueList .technique-row[data-technique-level="1"] { --yzf-technique-config-bg: #121c2d; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
  #techniqueList .technique-row[data-technique-level="2"] { --yzf-technique-config-bg: #143d2b; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
  #techniqueList .technique-row[data-technique-level="3"] { --yzf-technique-config-bg: #443b12; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
  #techniqueList .technique-row[data-technique-level="4"] { --yzf-technique-config-bg: #4a2b16; }
:root:is([data-yzf-theme="dark"], [data-yzf-theme="system"][data-yzf-resolved-theme="dark"])
  #techniqueList .technique-row[data-technique-level="5"] { --yzf-technique-config-bg: #4a2025; }