/* 注册颜色类型的自定义属性，让 gradient 能够平滑插值 */
@property --body-grad-1 {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(255, 255, 255, 0.58);
}
@property --body-grad-2 {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(255, 255, 255, 0.16);
}
@property --card-grad-1 {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(255, 255, 255, 0.84);
}
@property --card-grad-2 {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(250, 244, 234, 0.92);
}
/* 注意：--card-grad-base 故意不注册 @property，避免和 background-color
   shorthand 过渡叠加产生"末尾反弹闪烁"。它由 background-color 过渡负责。*/
@property --scroll-thumb {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(120, 110, 95, 0.45);
}
@property --scroll-track {
  syntax: "<color>";
  inherits: true;
  initial-value: rgba(0, 0, 0, 0.04);
}

:root {
  --bg: #f7f4ef;
  --panel: #fffdf9;
  --ink: #242424;
  --muted: #68645f;
  --line: #ded7cc;
  --accent: #246b61;
  --accent-dark: #174b44;
  --amber: #c97916;
  --red: #c24132;
  --green: #2f7d47;
  --gray: #9a948a;
  --blue: #3867ad;
  --purple: #8750a2;
  --radius: 8px;
  --shadow: 0 18px 44px rgba(54, 45, 34, 0.12);
  --body-grad-1: rgba(255, 255, 255, 0.58);
  --body-grad-2: rgba(255, 255, 255, 0.16);
  --card-grad-1: rgba(255, 255, 255, 0.84);
  --card-grad-2: rgba(250, 244, 234, 0.92);
  --card-grad-base: #fffdf8;
  --scroll-thumb: rgba(120, 110, 95, 0.45);
  --scroll-track: rgba(0, 0, 0, 0.04);
  font-family: Inter, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
}

/* 全局滚动条样式：跟随主题，颜色由 @property 变量驱动可平滑过渡 */
* {
  scrollbar-color: var(--scroll-thumb) var(--scroll-track);
  scrollbar-width: thin;
}
*::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}
*::-webkit-scrollbar-track {
  background-color: var(--scroll-track);
  border-radius: 8px;
}
*::-webkit-scrollbar-thumb {
  background-color: var(--scroll-thumb);
  border-radius: 8px;
  border: 2px solid transparent;
  background-clip: padding-box;
}
*::-webkit-scrollbar-thumb:hover {
  background-color: var(--scroll-thumb);
  filter: brightness(0.92);
}
*::-webkit-scrollbar-corner {
  background: transparent;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background:
    linear-gradient(180deg, var(--body-grad-1), var(--body-grad-2)),
    var(--bg);
}

button,
input,
textarea,
select {
  font: inherit;
}

/* iOS Safari：聚焦字号 < 16px 的输入框会自动放大页面（且不会自动缩回）。
   触屏设备统一把输入框设为 16px，杜绝聚焦放大；桌面不受影响，也不禁用手动缩放。 */
@media (pointer: coarse) {
  input,
  textarea,
  select {
    font-size: 16px;
  }
}

button {
  cursor: pointer;
}

.app-shell {
  width: min(1440px, 100%);
  margin: 0 auto;
  padding: 24px;
}

.site-footer {
  margin-top: 24px;
  padding: 16px 12px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 12px;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

.site-footer .footer-sep {
  opacity: 0.5;
}

.site-footer .footer-beian {
  color: var(--muted);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.site-footer .footer-beian:hover {
  color: var(--text);
  text-decoration: underline;
}

.site-footer .gongan-badge {
  height: 14px;
  width: auto;
  display: inline-block;
  vertical-align: -2px;
}

@media (max-width: 620px) {
  .site-footer {
    font-size: 11px;
    gap: 6px;
  }
  .site-footer .footer-sep {
    display: none;
  }
}

.topbar,
.stats-strip,
.activity-panel,
.workspace,
.import-panel,
.memory-panel {
  border: 1px solid var(--line);
  background: rgba(255, 253, 249, 0.88);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 18px;
  border-radius: var(--radius);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
  display: flex;
  align-items: center;
  gap: 7px;
}

.version-badge {
  display: inline-block;
  padding: 1px 7px;
  border: 1px solid rgba(36, 107, 97, 0.3);
  border-radius: 999px;
  background: rgba(36, 107, 97, 0.07);
  color: var(--accent);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.3px;
  text-transform: none;
  vertical-align: middle;
}

h1,
h2 {
  margin: 0;
  letter-spacing: 0;
}

h1 {
  font-size: clamp(22px, 2.6vw, 32px);
  line-height: 1.1;
}

h2 {
  font-size: 16px;
}

.top-actions,
.toolbar-actions,
.panel-head {
  display: flex;
  align-items: center;
  gap: 10px;
}

.top-actions {
  gap: 14px;
}

.overflow-menu-wrapper {
  position: relative;
}

.overflow-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 280px;
  max-width: calc(100vw - 32px);
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
  z-index: 30;
}

.overflow-menu[hidden] {
  display: none;
}

.overflow-menu-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  width: 100%;
  padding: 10px 12px;
  border: 0;
  background: transparent;
  text-align: left;
  border-radius: 6px;
  color: var(--ink);
  cursor: pointer;
  text-decoration: none;
}

.overflow-menu-item:hover,
.overflow-menu-item:focus-visible {
  background: rgba(0, 0, 0, 0.05);
  outline: none;
}

.overflow-menu-item.danger {
  color: var(--red);
}

.overflow-menu-item.danger:hover,
.overflow-menu-item.danger:focus-visible {
  background: rgba(194, 65, 50, 0.08);
}

.overflow-menu-icon {
  flex: 0 0 auto;
  width: 22px;          /* 固定图标列宽 + 居中：各项标题左缘对齐，不再参差 */
  text-align: center;
  margin-top: 1px;
  font-size: 16px;
  line-height: 1.3;
}

/* 菜单里若用单色 SVG 图标（如「新手引导」指南针），与同列文字图标对齐、同色 */
.overflow-menu-icon svg {
  width: 16px;
  height: 16px;
  vertical-align: -3px;
}

.overflow-menu-label {
  flex: 1 1 auto;
  min-width: 0;
}

.overflow-menu-label strong {
  display: block;
  margin-bottom: 3px;
  font-size: 14px;
  font-weight: 600;
}

.overflow-menu-label small {
  display: block;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.panel-head {
  justify-content: space-between;
}

.toolbar-actions {
  flex-wrap: wrap;
  justify-content: flex-end;
}

.toolbar-actions .secondary-button {
  min-width: 92px;
}

.primary-button,
.secondary-button,
.text-button,
.icon-button {
  border: 1px solid transparent;
  border-radius: var(--radius);
  min-height: 38px;
  padding: 0 14px;
  color: var(--ink);
  background: #fff;
}

.primary-button {
  color: #fff;
  background: var(--accent);
}

.primary-button:hover {
  background: var(--accent-dark);
}

.secondary-button {
  border-color: var(--line);
  background: #fff;
}

.text-button {
  color: var(--accent);
  background: transparent;
}

.close-import-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  min-height: 34px;
  padding: 0 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--muted);
  background: #fff;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.close-import-btn span {
  font-size: 14px;
  line-height: 1;
  opacity: 0.7;
}

.close-import-btn:hover {
  color: var(--ink);
  border-color: #bbb;
  background: var(--panel);
}

.close-import-btn:active {
  background: #e8e8e8;
}

.icon-button {
  width: 38px;
  padding: 0;
  border-color: var(--line);
  font-size: 18px;
  line-height: 1;
}

.stats-strip {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 1px;
  margin-top: 14px;
  overflow: hidden;
  border-radius: var(--radius);
}

.stat {
  min-width: 0;
  padding: 10px 14px;
  background: var(--panel);
}

.stat span {
  display: block;
  font-size: clamp(18px, 2.2vw, 26px);
  font-weight: 800;
  line-height: 1.1;
}

.stat small {
  color: var(--muted);
  font-size: 12px;
}

.activity-panel {
  margin-top: 10px;
  padding: 12px 14px;
  border-radius: var(--radius);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
}

.activity-summary {
  flex: 1 1 auto;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--line);
}

/* 热力图折叠开关：默认收起，只留一条三数字摘要带，避免喧宾夺主 */
.activity-toggle {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--muted);
  font-size: 12px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.activity-toggle:hover {
  color: var(--ink);
  border-color: var(--muted);
}

.activity-toggle-caret {
  font-size: 10px;
  transition: transform 0.18s ease;
}

.activity-panel.open .activity-toggle-caret {
  transform: rotate(180deg);
}

.activity-heatmap[hidden] {
  display: none;
}

.activity-summary div {
  min-width: 0;
  padding: 8px 10px;
  background: var(--panel);
}

.activity-summary span {
  display: block;
  font-size: 18px;
  font-weight: 800;
  line-height: 1.1;
}

.activity-summary small {
  color: var(--muted);
  font-size: 11px;
  white-space: nowrap;
}

.activity-heatmap {
  flex: 1 1 100%;
  display: grid;
  grid-template-columns: repeat(13, 1fr);
  grid-auto-rows: 12px;
  gap: 4px;
  min-width: 0;
  margin-top: 2px;
}

.heatmap-cell {
  display: block;
  min-width: 0;
  border-radius: 3px;
  background: rgba(104, 100, 95, 0.14);
  border: 1px solid rgba(104, 100, 95, 0.12);
}

.heatmap-cell.level-1 { background: rgba(36, 107, 97, 0.22); border-color: rgba(36, 107, 97, 0.12); }
.heatmap-cell.level-2 { background: rgba(36, 107, 97, 0.38); border-color: rgba(36, 107, 97, 0.18); }
.heatmap-cell.level-3 { background: rgba(36, 107, 97, 0.58); border-color: rgba(36, 107, 97, 0.24); }
.heatmap-cell.level-4 { background: rgba(36, 107, 97, 0.82); border-color: rgba(36, 107, 97, 0.32); }

.import-panel {
  margin-top: 14px;
  padding: 18px;
  border-radius: var(--radius);
}

.import-mode {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 14px;
}

.import-mode-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 2px solid var(--line);
  border-radius: var(--radius);
  cursor: pointer;
  background: var(--panel);
  transition: border-color 0.15s, background 0.15s, box-shadow 0.15s;
  user-select: none;
}

.import-mode-card input[type="radio"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  pointer-events: none;
}

.import-mode-icon {
  font-size: 20px;
  line-height: 1;
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  font-style: normal;
}

.import-mode-body {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.import-mode-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.2;
}

.import-mode-desc {
  font-size: 11.5px;
  color: var(--muted);
  line-height: 1.4;
}

/* 追加新词 — 默认绿色系 */
.import-mode-append .import-mode-icon {
  background: #e6f4ec;
  color: var(--green);
}

.import-mode-append:hover {
  border-color: var(--green);
  background: #f2faf5;
}

.import-mode-append:has(input:checked) {
  border-color: var(--green);
  background: #f2faf5;
  box-shadow: 0 0 0 3px rgba(47, 125, 71, 0.12);
}

.import-mode-append:has(input:checked) .import-mode-title {
  color: var(--green);
}

/* 替换全部 — 红色警示 */
.import-mode-replace .import-mode-icon {
  background: #fdecea;
  color: var(--red);
}

.import-mode-replace:hover {
  border-color: #e8a09a;
  background: #fff8f7;
}

.import-mode-replace:has(input:checked) {
  border-color: var(--red);
  background: #fff8f7;
  box-shadow: 0 0 0 3px rgba(194, 65, 50, 0.12);
}

.import-mode-replace:has(input:checked) .import-mode-title {
  color: var(--red);
}

.import-tabs {
  display: flex;
  gap: 2px;
  margin-top: 14px;
  border-bottom: 1px solid var(--line);
}

.import-tab {
  padding: 7px 18px;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  background: transparent;
  color: var(--muted);
  font-size: 13px;
  border-radius: 6px 6px 0 0;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.import-tab:hover {
  color: var(--ink);
}

.import-tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 500;
}

.import-tab-body {
  margin-top: 14px;
}

.wordbook-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 10px;
}

.wordbook-card {
  min-width: 0;
  min-height: 104px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 6px;
  transition: border-color 0.15s, background-color 0.15s, transform 0.15s;
}

.wordbook-card:hover:not(:disabled),
.wordbook-card:focus-visible {
  border-color: rgba(36, 107, 97, 0.45);
  background: #f7fbf7;
  transform: translateY(-1px);
  outline: none;
}

.wordbook-card:disabled {
  cursor: wait;
  opacity: 0.72;
}

.wordbook-card strong {
  font-size: 14px;
  line-height: 1.2;
}

.wordbook-card span {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.35;
  flex: 1;
}

.wordbook-card small {
  color: var(--accent);
  font-size: 11px;
  font-weight: 600;
}

.wordbook-note {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 12px;
}

.ai-convert-box {
  display: grid;
  gap: 10px;
}

.ai-convert-controls {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  align-items: center;
}

.ai-convert-controls input[type="text"] {
  width: auto;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0 12px;
  background: #fff;
}

.ai-convert-result {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.ai-convert-result-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 12px;
  background: #f5f2ec;
  border-bottom: 1px solid var(--line);
  font-size: 13px;
  color: var(--muted);
}

.ai-convert-result textarea {
  display: block;
  border: none;
  border-radius: 0;
  min-height: 160px;
  background: #fdfaf5;
  font-family: "Courier New", Consolas, monospace;
  font-size: 12px;
  line-height: 1.7;
}

.file-drop {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 150px;
  padding: 28px 18px;
  border: 2px dashed var(--line);
  border-radius: var(--radius);
  color: var(--muted);
  text-align: center;
  background: #faf7f0;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}

.file-drop input {
  display: none;
}

.file-drop:hover,
.file-drop.drag-over {
  border-color: var(--accent);
  background: #f0f7f5;
}

.file-drop-icon {
  width: 36px;
  height: 36px;
  color: var(--gray);
  margin-bottom: 4px;
  transition: color 0.15s;
}

.file-drop:hover .file-drop-icon,
.file-drop.drag-over .file-drop-icon {
  color: var(--accent);
}

.file-drop-title {
  font-size: 13.5px;
  color: var(--ink);
  font-weight: 500;
}

.file-drop-title em {
  font-style: normal;
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.file-drop-hint {
  font-size: 12px;
  color: var(--muted);
  margin-top: 2px;
}

.paste-box {
  display: grid;
  gap: 10px;
}

textarea {
  width: 100%;
  min-height: 150px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px;
  background: #fff;
}

.hint {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.workspace {
  display: grid;
  grid-template-columns: 340px minmax(0, 1fr);
  gap: 0;
  margin-top: 10px;
  /* 不再写死高度：整页作为唯一滚动容器，工作区随 study-area 内容自然增高。
     min-height 给左侧词表一个基线高度，避免内容很少时列表太矮。 */
  min-height: clamp(460px, calc(100vh - 220px), 720px);
  border-radius: var(--radius);
  overflow: hidden;
}

.overview {
  display: flex;
  flex-direction: column;
  height: auto;
  align-self: stretch;   /* 跟随 workspace 行高：左列与 study-area 始终等高 */
  min-height: 0;
  padding: 18px;
  border-right: 1px solid var(--line);
  background: rgba(255, 253, 249, 0.72);
}

select,
.search-input,
.ai-settings input {
  width: 100%;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0 11px;
  background: #fff;
}

/* 反馈表单：下拉与多行输入（暗色由通用 textarea/select 规则覆盖） */
.feedback-form select {
  width: 100%;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0 11px;
  background: #fff;
  color: inherit;
  font: inherit;
}

.feedback-form textarea {
  width: 100%;
  min-height: 104px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 9px 11px;
  background: #fff;
  color: inherit;
  font: inherit;
  line-height: 1.55;
  resize: vertical;
}

.search-input {
  margin-top: 14px;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin: 14px 0;
  color: var(--muted);
  font-size: 12px;
}

.dot {
  display: inline-block;
  width: 9px;
  height: 9px;
  margin-right: 5px;
  border-radius: 50%;
  vertical-align: 1px;
}

.dot.new {
  background: var(--gray);
}

.dot.learning {
  background: var(--amber);
}

.dot.due {
  background: var(--red);
}

.dot.mastered {
  background: var(--green);
}

.word-list {
  position: relative;
  display: block;
  flex: 1 1 auto;
  /* 词表自身保持虚拟滚动（3600+ 条必须）。contain:size 让虚拟列表的撑高占位条
     不参与左列的固有高度计算，词表才能 flex 填满左列剩余空间——左列高度由
     workspace 行高（即 study-area）决定，两列始终等高。 */
  contain: size;
  min-height: 220px;
  overflow: auto;
  padding-right: 4px;
}

.word-list-spacer {
  width: 1px;
  pointer-events: none;
}

.word-item {
  position: absolute;
  top: 0;
  left: 0;
  right: 4px;
  display: grid;
  grid-template-columns: auto 1fr auto auto auto;
  align-items: center;
  gap: 6px;
  min-height: 38px;
  height: 38px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  padding: 7px 8px;
  text-align: left;
  background: transparent;
  cursor: pointer;
  font: inherit;
  color: inherit;
}

.word-item:hover,
.word-item.active {
  border-color: var(--line);
  background: #fff;
}

.word-item strong {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.word-item small {
  color: var(--muted);
  margin-right: 2px;
}

.word-item-action {
  width: 24px;
  height: 24px;
  display: inline-grid;
  place-items: center;
  border: 0;
  background: transparent;
  color: var(--muted);
  font-size: 15px;
  line-height: 1;
  padding: 0;
  border-radius: 4px;
  opacity: 0;
  transition: opacity 0.15s, color 0.15s, background 0.15s;
}

.word-item:hover .word-item-action,
.word-item.active .word-item-action,
.word-item-action.starred {
  opacity: 1;
}

.word-item-action:hover {
  background: rgba(0, 0, 0, 0.06);
}

.word-item-action.star.starred {
  color: var(--amber);
}

.word-item-action.delete:hover {
  color: var(--red);
}

.overview-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.overview-actions select {
  min-height: 32px;
  width: auto;
  padding: 0 8px;
}

/* 自定义筛选下拉框：替换原生 <select> 的展开列表，统一暖色主题 */
.cute-select {
  position: relative;
  display: inline-block;
}
.cute-select .cute-select-native {
  display: none;
}
.cute-select-trigger {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 32px;
  padding: 0 9px 0 11px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  font: inherit;
  font-size: 14px;
  line-height: 1;
  cursor: pointer;
  transition: border-color 0.15s, box-shadow 0.15s, background 0.15s;
}
.cute-select-trigger:hover {
  border-color: var(--accent);
}
.cute-select-trigger:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(36, 107, 97, 0.16);
}
.cute-select.is-open .cute-select-trigger {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(36, 107, 97, 0.16);
}
.cute-select-label {
  white-space: nowrap;
}
.cute-select-chevron {
  flex: none;
  color: var(--muted);
  transition: transform 0.18s ease, color 0.18s ease;
}
.cute-select.is-open .cute-select-chevron {
  transform: rotate(180deg);
  color: var(--accent);
}

.cute-select-menu {
  position: absolute;
  z-index: 60;
  top: calc(100% + 6px);
  left: 0;
  min-width: 100%;
  width: max-content;
  padding: 6px;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  box-shadow: var(--shadow);
  max-height: 320px;
  overflow-y: auto;
  animation: cuteSelectIn 0.14s ease;
}
@keyframes cuteSelectIn {
  from {
    opacity: 0;
    transform: translateY(-4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
.cute-select-option {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-radius: 7px;
  font-size: 14px;
  color: var(--ink);
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.12s, color 0.12s;
}
.cute-select-option:hover,
.cute-select-option:focus-visible {
  outline: none;
  background: rgba(36, 107, 97, 0.08);
}
.cute-select-option.is-selected {
  color: var(--accent);
  font-weight: 600;
  background: rgba(36, 107, 97, 0.1);
}
.cute-select-check {
  flex: none;
  width: 15px;
  height: 15px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  opacity: 0;
}
.cute-select-option.is-selected .cute-select-check {
  opacity: 1;
}

[data-theme="dark"] .cute-select-option:hover,
[data-theme="dark"] .cute-select-option:focus-visible {
  background: rgba(255, 255, 255, 0.06);
}
[data-theme="dark"] .cute-select-option.is-selected {
  background: rgba(45, 150, 135, 0.16);
}

#shuffleBtn,
#exportBtn {
  width: 32px;
  min-height: 32px;
  padding: 0;
  display: inline-grid;
  place-items: center;
}

#shuffleBtn svg,
#exportBtn svg {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.undo-toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 16px;
  background: var(--ink);
  color: #fff;
  border-radius: var(--radius);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.22);
  z-index: 100;
  font-size: 14px;
  animation: toastIn 220ms ease;
}

.undo-toast[hidden] {
  display: none;
}

.undo-toast .text-button {
  color: #ffd87b;
  padding: 0 6px;
  min-height: auto;
  background: transparent;
}

@keyframes toastIn {
  from { opacity: 0; transform: translate(-50%, 14px); }
  to { opacity: 1; transform: translate(-50%, 0); }
}

.success-toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: #237a4b;
  color: #fff;
  border-radius: var(--radius);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.22);
  z-index: 101;
  font-size: 14px;
  animation: toastIn 220ms ease;
}

.success-toast[hidden] {
  display: none;
}

@media (max-width: 620px) {
  .overflow-menu {
    min-width: 240px;
    max-width: calc(100vw - 16px);
  }

  .undo-toast {
    bottom: calc(80px + env(safe-area-inset-bottom));
    left: 12px;
    right: 12px;
    transform: none;
    justify-content: space-between;
  }

  .success-toast {
    bottom: calc(80px + env(safe-area-inset-bottom));
    left: 12px;
    right: 12px;
    transform: none;
  }

  @keyframes toastIn {
    from { opacity: 0; transform: translateY(14px); }
    to { opacity: 1; transform: translateY(0); }
  }
}

.study-area {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
  min-height: 0;
  /* 去掉 height:100% 与 overflow:auto —— 卡片/评分/AI 区随整页滚动，
     鼠标停在卡片区滚轮即滚动整页，不再被局部滚动容器吃掉。
     左侧词表（.word-list）仍保留自身滚动：3600+ 条必须虚拟滚动。 */
  padding: 16px 18px;
}

.study-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.toolbar-info {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.toolbar-info-row {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.queue-label {
  display: block;
  margin-bottom: 3px;
  color: var(--muted);
  font-size: 13px;
}

.progress-bar {
  position: relative;
  width: 100%;
  max-width: 320px;
  height: 6px;
  border-radius: 999px;
  background: rgba(36, 107, 97, 0.12);
  overflow: hidden;
}

.progress-bar[hidden] {
  display: none;
}

.progress-bar-fill {
  position: absolute;
  inset: 0 auto 0 0;
  width: 0%;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), #4f9b8e);
  transition: width 0.45s cubic-bezier(0.22, 0.61, 0.36, 1), background 0.3s ease;
}

.progress-bar.complete .progress-bar-fill {
  background: linear-gradient(90deg, var(--green), #5fa775);
}

.celebration {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 320px;
  padding: 40px 24px;
  text-align: center;
  border: 1px solid rgba(47, 125, 71, 0.28);
  border-radius: var(--radius);
  background:
    radial-gradient(circle at 50% -20%, rgba(47, 125, 71, 0.18), transparent 55%),
    linear-gradient(155deg, #f0faf3, #fdfaf3);
  box-shadow: var(--shadow);
  animation: celebrationIn 320ms ease;
}

.celebration[hidden] {
  display: none;
}

@keyframes celebrationIn {
  from {
    opacity: 0;
    transform: translateY(8px) scale(0.985);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.celebration-icon {
  font-size: 56px;
  line-height: 1;
  filter: drop-shadow(0 4px 12px rgba(47, 125, 71, 0.25));
}

.celebration-title {
  margin: 6px 0 4px;
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 800;
  color: var(--green);
  letter-spacing: 0;
}

.celebration-stat,
.celebration-next {
  margin: 0;
  color: #4d4942;
  font-size: 14px;
  line-height: 1.6;
}

.celebration-stat strong,
.celebration-next strong {
  margin: 0 4px;
  color: var(--ink);
  font-weight: 800;
  font-size: 17px;
}

.celebration-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-top: 14px;
}

.celebration-btn {
  min-height: 42px;
  padding: 0 22px;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 700;
  border: 1.5px solid transparent;
  transition: background 0.15s, border-color 0.15s, transform 0.12s;
}

.celebration-btn[hidden] {
  display: none;
}

.celebration-btn.primary {
  color: #fff;
  background: var(--green);
  border-color: var(--green);
}

.celebration-btn.primary:hover {
  background: #266a3a;
  border-color: #266a3a;
  transform: translateY(-1px);
}

.celebration-btn.secondary {
  color: var(--green);
  background: #fff;
  border-color: rgba(47, 125, 71, 0.45);
}

.celebration-btn.secondary:hover {
  background: #f0faf3;
  border-color: var(--green);
  transform: translateY(-1px);
}

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  min-height: 320px;
  padding: 40px 24px;
  text-align: center;
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  background: rgba(255, 253, 249, 0.6);
}

.empty-state[hidden] {
  display: none;
}

.empty-state-icon {
  color: var(--accent);
  opacity: 0.85;
}

.empty-state-title {
  margin: 4px 0 0;
  font-size: clamp(20px, 2.4vw, 26px);
  font-weight: 800;
}

.empty-state-desc {
  margin: 0;
  max-width: 460px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.65;
}

.primary-button-lg {
  min-height: 46px;
  padding: 0 28px;
  margin-top: 4px;
  font-size: 15px;
  font-weight: 700;
}

.empty-state-hint {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 12px;
}

.empty-state-hint code {
  padding: 1px 6px;
  border-radius: 4px;
  background: rgba(36, 107, 97, 0.08);
  color: var(--accent);
  font-family: "Courier New", Consolas, monospace;
  font-size: 12px;
}

.flashcard-shell {
  position: relative;
  flex: 0 0 auto;
}

.flashcard {
  display: block;
  width: 100%;
  height: clamp(200px, calc(100vh - 430px), 360px);
  min-height: 200px;
  max-height: 360px;
  overflow: visible;
  border: 0;
  border-radius: var(--radius);
  padding: 0;
  color: var(--ink);
  background: transparent;
  perspective: 1400px;
  text-align: center;
  white-space: normal;
  cursor: pointer;
  transition: transform 0.2s ease;
}

@media (hover: hover) {
  .flashcard:hover {
    transform: translateY(-2px);
  }

  .flashcard:hover .card-face {
    box-shadow: 0 26px 56px rgba(54, 45, 34, 0.18);
  }

  .flashcard:hover .flip-hint-icon {
    transform: rotate(-25deg);
  }
}

.flashcard:active {
  transform: translateY(0);
}

.card-actions {
  position: absolute;
  top: 12px;
  right: 12px;
  z-index: 3;
  display: flex;
  align-items: center;
  gap: 6px;
}

.card-action {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border: 1px solid rgba(222, 215, 204, 0.7);
  border-radius: 50%;
  color: var(--muted);
  background: rgba(255, 253, 249, 0.7);
  backdrop-filter: blur(4px);
  font-size: 16px;
  line-height: 1;
  padding: 0;
  transition: color 0.15s, background 0.15s, border-color 0.15s, transform 0.15s;
}

.card-action:hover {
  color: var(--amber);
  background: #fff;
  border-color: rgba(201, 121, 22, 0.36);
  transform: translateY(-1px);
}

.card-favorite.starred {
  color: var(--amber);
  background: #fff8e6;
  border-color: rgba(201, 121, 22, 0.42);
}

.card-delete:hover {
  color: var(--red);
  border-color: rgba(194, 65, 50, 0.34);
}

/* 静态：只显示第一条波纹，另两条淡出 */
.card-speak .speak-w2,
.card-speak .speak-w3 {
  opacity: 0.25;
  transition: opacity 0.2s;
}

/* 播放中：三条波纹依次延迟脉冲 */
.card-action.card-speak.speaking {
  color: var(--accent);
  border-color: rgba(36, 107, 97, 0.5);
  background: rgba(36, 107, 97, 0.08);
}

.card-speak.speaking .speak-w1 {
  animation: speakPulse 1.1s ease-in-out infinite;
}
.card-speak.speaking .speak-w2 {
  opacity: 1;
  animation: speakPulse 1.1s ease-in-out 0.22s infinite;
}
.card-speak.speaking .speak-w3 {
  opacity: 1;
  animation: speakPulse 1.1s ease-in-out 0.44s infinite;
}

@keyframes speakPulse {
  0%, 100% { opacity: 0.2; }
  50%      { opacity: 1;   }
}

.card-action:disabled {
  cursor: default;
  opacity: 0.45;
  transform: none;
}

.card-inner {
  position: relative;
  display: block;
  width: 100%;
  height: 100%;
  min-height: 260px;
  transform-style: preserve-3d;
  transition: transform 520ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.flashcard.revealed .card-inner {
  transform: rotateY(180deg);
}

.flashcard.slide-next .card-inner {
  animation: slideNext 260ms ease;
}

.flashcard.slide-prev .card-inner {
  animation: slidePrev 260ms ease;
}

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  height: 100%;
  min-height: 200px;
  max-height: 360px;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(18px, 3vw, 32px);
  /* 卡片底色用 background-color 长属性驱动，主题切换时可在所有浏览器平滑过渡
     （不依赖 @property 对 gradient 变量插值，老版本移动 Safari 也能过渡）。
     上层只叠一层与主题无关的淡高光，因此无需对渐变本身做过渡。 */
  background-color: var(--card-grad-base);
  background-image: linear-gradient(150deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0) 62%);
  box-shadow: var(--shadow);
  backface-visibility: hidden;
  transition: box-shadow 0.2s ease, background-color 0.34s ease, border-color 0.34s ease;
}

.card-back {
  justify-content: center;
  transform: rotateY(180deg);
  padding-top: clamp(20px, 3vw, 36px);
}

.back-label {
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
}

.flip-hint {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.1px;
}

.flip-hint-icon {
  width: 14px;
  height: 14px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: 0.85;
  transition: transform 0.28s ease;
}

.word {
  max-width: 100%;
  overflow-wrap: anywhere;
  font-size: clamp(36px, 5.4vw, 64px);
  font-weight: 850;
  line-height: 1;
}

.flashcard.revealed .word {
  font-size: clamp(30px, 4.4vw, 52px);
}

.phonetic {
  min-height: 24px;
  color: #5b554e;
  font-size: clamp(16px, 1.6vw, 20px);
}

.pos-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  min-height: 30px;
  width: min(820px, 100%);
  flex: 0 0 auto;
}

.pos-tag {
  display: inline-grid;
  place-items: center;
  min-height: 28px;
  border-radius: 999px;
  padding: 0 11px;
  color: #fff;
  font-size: 13px;
  font-weight: 700;
}

.pos-n {
  background: var(--blue);
}

.pos-v,
.pos-vt,
.pos-vi {
  background: var(--green);
}

.pos-a,
.pos-adj {
  background: var(--amber);
}

.pos-ad,
.pos-adv {
  background: var(--purple);
}

.pos-other {
  background: #6d6259;
}

.definition {
  display: block;
  width: min(820px, 100%);
  min-height: 3.6em;
  max-height: 160px;
  flex: 0 1 auto;
  overflow: auto;
  margin-top: 2px;
  padding: 6px 10px;
  color: #2f2b27;
  font-size: clamp(16px, 2vw, 24px);
  font-weight: 650;
  line-height: 1.45;
  text-align: center;
  white-space: normal;
  word-break: normal;
  line-break: anywhere;
  overflow-wrap: anywhere;
}

.flashcard.revealed .flip-hint {
  color: var(--accent);
}

/* ===== 拼写练习（翻面后释义下方常驻输入框，点击即用）===== */
.card-spell-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: min(420px, 100%);
  margin-top: 6px;
}

.card-spell-input {
  width: 100%;
  border: 1.5px solid var(--line);
  border-radius: 12px;
  padding: 10px 14px;
  background: rgba(255, 255, 255, 0.92);
  color: var(--ink);
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-align: center;
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.card-spell-input::placeholder {
  color: var(--muted);
  font-weight: 500;
  font-size: 14px;
  letter-spacing: normal;
}

.card-spell-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(36, 107, 97, 0.14);
}

.card-spell-input.correct {
  border-color: var(--green);
  box-shadow: 0 0 0 3px rgba(47, 125, 71, 0.16);
}

.card-spell-input.wrong {
  border-color: var(--red);
  box-shadow: 0 0 0 3px rgba(194, 65, 50, 0.15);
}

.card-spell-feedback {
  min-height: 1em;
  font-size: 13px;
  font-weight: 700;
}

.card-spell-feedback.correct {
  color: var(--green);
}

.card-spell-feedback.wrong {
  color: var(--red);
}

[data-theme="dark"] .card-spell-input {
  background: #2e2c28;
  border-color: var(--line);
  color: var(--ink);
}

/* ===== 新手引导（首次登录分步引导）===== */
.tour-overlay {
  position: fixed;
  inset: 0;
  z-index: 9999;
}
.tour-overlay.dim {
  background: rgba(0, 0, 0, 0.55);
}
body.tour-open {
  overflow: hidden;
}
.tour-spot {
  position: fixed;
  border-radius: 10px;
  box-shadow: 0 0 0 9999px rgba(0, 0, 0, 0.55);
  pointer-events: none;
  transition: left 0.2s ease, top 0.2s ease, width 0.2s ease, height 0.2s ease;
}
.tour-pop {
  position: fixed;
  width: min(330px, calc(100vw - 24px));
  background: var(--panel, #fffdf9);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.28);
  padding: 16px 18px;
}
.tour-pop-step {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 6px;
}
.tour-pop-title {
  margin: 0 0 6px;
  font-size: 16px;
  font-weight: 800;
}
.tour-pop-body {
  margin: 0 0 14px;
  font-size: 13.5px;
  line-height: 1.6;
  color: var(--ink);
}
.tour-pop-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}
.tour-pop-right {
  display: inline-flex;
  gap: 8px;
}
.tour-pop-actions button {
  border-radius: 8px;
  padding: 7px 14px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--muted);
  transition: background 0.15s, color 0.15s, border-color 0.15s, filter 0.15s;
}
.tour-skip:hover,
.tour-prev:hover {
  color: var(--ink);
  border-color: var(--muted);
}
.tour-next {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.tour-next:hover {
  filter: brightness(0.93);
}
[data-theme="dark"] .tour-pop {
  background: #252420;
  border-color: var(--line);
}

@keyframes slideNext {
  0% {
    opacity: 0;
    transform: translateX(28px) scale(0.985);
  }
  100% {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
}

@keyframes slidePrev {
  0% {
    opacity: 0;
    transform: translateX(-28px) scale(0.985);
  }
  100% {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
}

.rating-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin: 0;
}

kbd {
  display: inline-grid;
  place-items: center;
  min-width: 18px;
  height: 18px;
  margin-left: 4px;
  padding: 0 5px;
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: #fff;
  color: var(--muted);
  font: 600 11px/1 "Courier New", Consolas, monospace;
  vertical-align: 2px;
}

.rating strong kbd {
  background: rgba(255, 255, 255, 0.85);
}

.rating {
  min-height: 54px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
  padding: 6px 8px;
  transition: transform 0.12s ease, box-shadow 0.12s ease, border-color 0.12s ease;
}

.rating:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(54, 45, 34, 0.08);
}

.rating:disabled {
  background: #f4f0e9;
}

.rating.again {
  border-color: rgba(109, 98, 89, 0.55);
  background: #efeae0;
}

.rating.again:hover:not(:disabled) {
  background: #e7e0d3;
}

.rating strong,
.rating span {
  display: block;
}

.rating span {
  margin-top: 3px;
  color: var(--muted);
  font-size: 13px;
}

.rating.hard {
  border-color: rgba(194, 65, 50, 0.55);
  background: #fbe9e5;
}

.rating.hard:hover:not(:disabled) {
  background: #f8d8d1;
}

.rating.good {
  border-color: rgba(201, 121, 22, 0.55);
  background: #fcf2dc;
}

.rating.good:hover:not(:disabled) {
  background: #fae5be;
}

.rating.easy {
  border-color: rgba(47, 125, 71, 0.55);
  background: #e6f0e6;
}

.rating.easy:hover:not(:disabled) {
  background: #d6e8d6;
}

.rating {
  border-width: 1.5px;
}

/* 亮色模式下显式指定难度文字颜色，否则 iOS Safari 会把 <button> 内文字
   渲染成系统蓝色（桌面端默认黑色，所以只在移动端暴露）。 */
.rating strong {
  color: var(--ink);
}
.rating.again strong { color: #6d6259; }
.rating.hard strong  { color: var(--red); }
.rating.good strong  { color: var(--amber); }
.rating.easy strong  { color: var(--green); }

.memory-panel {
  display: grid;
  gap: 12px;
  padding: 14px 16px 16px;
  border-radius: var(--radius);
  background:
    linear-gradient(135deg, rgba(36, 107, 97, 0.08), rgba(36, 107, 97, 0.02)),
    var(--panel);
  border: 1px solid rgba(36, 107, 97, 0.22);
  box-shadow: 0 1px 0 rgba(36, 107, 97, 0.04), 0 6px 18px rgba(36, 107, 97, 0.06);
}

.memory-panel .panel-head h2 {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--accent-dark);
}

.memory-panel .panel-head h2::before {
  content: "✦";
  color: var(--accent);
  font-size: 15px;
  line-height: 1;
}

.memory-panel #generateMemoryBtn,
.memory-panel #lookupBtn {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  font-weight: 600;
}

.memory-panel #generateMemoryBtn:hover:not(:disabled),
.memory-panel #lookupBtn:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
}

.memory-panel #generateMemoryBtn:disabled {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.ai-settings {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

.ai-settings label {
  display: grid;
  gap: 5px;
  color: var(--muted);
  font-size: 13px;
}

/* 「记住我的 Key」勾选框：与文字同一行（覆盖上面 .ai-settings label 的 grid 堆叠） */
.ai-settings label.remember-key-row {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 8px;
}

.ai-settings label.remember-key-row input {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  accent-color: var(--accent);
  cursor: pointer;
}

.field-note {
  color: var(--muted);
  font-size: 11px;
  line-height: 1.35;
}

/* API modal overlay */
.api-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
  padding: 20px;
}

.api-modal-overlay[hidden] {
  display: none;
}

.api-modal {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 20px 24px 24px;
  width: 100%;
  max-width: 480px;
  box-shadow: var(--shadow);
  display: grid;
  gap: 18px;
}

.api-modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.api-modal-head h2 {
  font-size: 16px;
  font-weight: 600;
  margin: 0;
}

.api-modal-note {
  font-size: 12px;
  color: var(--muted);
  line-height: 1.45;
  margin: 0;
}

/* API Key 获取指引（可折叠） */
/* API Key 获取教程入口（点击在新窗口打开独立教程页 apikey-guide.html） */
.apikey-guide-entry {
  margin-top: -6px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  color: var(--accent, #246b61);
  font-size: 12.5px;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s;
}

.apikey-guide-entry:hover {
  background: rgba(36, 107, 97, 0.08);
  border-color: var(--accent, #246b61);
}

.apikey-guide-entry-arrow {
  font-size: 13px;
  flex-shrink: 0;
}

/* Donate modal */
.donate-modal {
  max-width: 440px;
  text-align: center;
}

.donate-modal .api-modal-head h2 span {
  color: #e0245e;
}

.donate-intro {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.6;
  margin: 0;
  text-align: left;
}

.donate-intro strong {
  color: var(--text);
  font-weight: 600;
}

.donate-qr-row {
  display: flex;
  gap: 16px;
  justify-content: center;
}

.donate-qr {
  flex: 1;
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 14px 10px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--bg);
}

.donate-qr img {
  width: 100%;
  max-width: 168px;
  aspect-ratio: 1 / 1;
  object-fit: contain;
  border-radius: 8px;
  display: block;
}

.donate-qr-placeholder {
  display: none;
  width: 100%;
  max-width: 168px;
  aspect-ratio: 1 / 1;
  border: 1px dashed var(--line);
  border-radius: 8px;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  color: var(--muted);
  line-height: 1.5;
}

.donate-qr-placeholder small {
  font-size: 10px;
  opacity: 0.8;
}

.donate-qr-missing img {
  display: none;
}

.donate-qr-missing .donate-qr-placeholder {
  display: flex;
  flex-direction: column;
}

.donate-qr figcaption {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
}

.donate-qr-wechat figcaption {
  color: #07c160;
}

.donate-qr-alipay figcaption {
  color: #1677ff;
}

.donate-intl-link[hidden] {
  display: none;
}

.donate-intl-link {
  display: inline-block;
  font-size: 13px;
  color: var(--accent, #1677ff);
  text-decoration: none;
  padding: 8px 0;
}

.donate-intl-link:hover {
  text-decoration: underline;
}

/* Overflow menu divider */
.overflow-divider {
  height: 1px;
  background: var(--line);
  margin: 4px 0;
}

/* API hint below AI buttons */
.api-hint {
  font-size: 12px;
  color: var(--muted);
  margin: 0;
  line-height: 1.4;
}

.api-hint[hidden] {
  display: none;
}

.api-hint-link {
  background: none;
  border: none;
  padding: 0;
  color: var(--accent);
  cursor: pointer;
  font-size: 12px;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.api-hint-link:hover {
  color: var(--accent-dark);
}

.memory-panel-btns {
  display: flex;
  gap: 8px;
}

.sentence-content {
  max-height: 160px;
  overflow: auto;
  color: var(--ink);
  line-height: 1.75;
  white-space: pre-wrap;
  font-size: 13.5px;
  padding: 10px 12px;
  background: rgba(56, 103, 173, 0.05);
  border: 1px solid rgba(56, 103, 173, 0.18);
  border-radius: 6px;
}

.sentence-content[hidden] {
  display: none;
}

.memory-content {
  max-height: 220px;
  min-height: 56px;
  overflow: auto;
  color: var(--ink);
  line-height: 1.7;
  white-space: pre-wrap;
  font-size: 14px;
  padding: 10px 12px;
  background: rgba(255, 253, 249, 0.85);
  border: 1px solid rgba(36, 107, 97, 0.14);
  border-radius: 6px;
}

.memory-lookup {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
  margin-top: 4px;
}

.memory-lookup input {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0 12px;
  background: #fff;
}

.memory-lookup input:focus {
  outline: 2px solid rgba(36, 107, 97, 0.25);
  outline-offset: 1px;
}

.memory-lookup button {
  white-space: nowrap;
}

.secondary-button:disabled,
.primary-button:disabled,
.rating:disabled {
  cursor: not-allowed;
  opacity: 0.56;
}

/* Mobile tab bar — hidden on desktop */
.mobile-tab-bar {
  display: none;
}

@media (max-width: 980px) {
  .workspace {
    display: flex;
    flex-direction: column;
    height: auto;
    min-height: 0;
  }

  /* Tab bar */
  .mobile-tab-bar {
    display: flex;
    flex-shrink: 0;
    border-bottom: 1px solid var(--line);
    background: var(--panel);
  }

  .mobile-tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 10px 12px;
    border: none;
    border-bottom: 2px solid transparent;
    margin-bottom: -1px;
    background: transparent;
    color: var(--muted);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: color 0.15s, border-color 0.15s;
  }

  .mobile-tab svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
  }

  .mobile-tab:hover {
    color: var(--ink);
  }

  .mobile-tab.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
  }

  /* Panels: hidden unless active */
  .overview {
    display: none;
    max-height: 100%;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    flex: 1;
    min-height: 400px;
    /* 移动端为纵向 flex：抵消桌面的 align-self:start，让总览铺满整宽、不再偏左 */
    align-self: stretch;
  }

  .overview.mobile-active {
    display: flex;
  }

  /* 移动端词表跟随整页滚动（窗口级虚拟滚动）：恢复固有高度（占位条撑开列表），
     页面滚动而非列表内部滚动 */
  .word-list {
    contain: none;
    max-height: none;
    min-height: 0;
  }

  .study-area {
    flex: 1;
  }

  .study-area.mobile-hidden {
    display: none;
  }

  .ai-convert-controls {
    grid-template-columns: 1fr;
  }

  .activity-panel {
    grid-template-columns: 1fr;
  }

  .wordbook-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 620px) {
  .app-shell {
    padding: 12px;
  }

  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .topbar .top-actions {
    align-self: flex-end;
  }

  .stats-strip {
    grid-template-columns: repeat(5, 1fr);
    margin-top: 10px;
  }

  .activity-panel {
    margin-top: 10px;
    padding: 10px;
  }

  .activity-summary div {
    padding: 7px 6px;
    text-align: center;
  }

  .activity-summary span {
    font-size: 16px;
  }

  .activity-summary small {
    font-size: 10.5px;
  }

  .activity-heatmap {
    grid-auto-rows: 10px;
    gap: 3px;
  }

  .stat {
    padding: 7px 4px;
    text-align: center;
  }

  .stat span {
    font-size: 17px;
    line-height: 1.15;
  }

  .stat small {
    display: block;
    margin-top: 1px;
    font-size: 10.5px;
    line-height: 1.2;
    letter-spacing: -0.2px;
    white-space: nowrap;
  }

  .flashcard {
    touch-action: pan-y;
  }

  .rating-row {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    grid-template-columns: repeat(4, 1fr);
    gap: 6px;
    margin: 0;
    padding: 8px 10px calc(8px + env(safe-area-inset-bottom));
    background: rgba(255, 253, 249, 0.96);
    border-top: 1px solid var(--line);
    box-shadow: 0 -8px 24px rgba(54, 45, 34, 0.08);
    backdrop-filter: blur(8px);
    z-index: 50;
  }

  .rating {
    min-height: 52px;
    padding: 6px 4px;
  }

  .rating strong {
    font-size: 13px;
  }

  .rating strong kbd {
    display: none;
  }

  .rating span {
    margin-top: 2px;
    font-size: 11px;
  }

  .study-area {
    grid-template-rows: auto minmax(280px, auto) auto auto auto;
    padding: 14px 14px 96px;
  }

  .flashcard-shell {
    margin-bottom: 22px;
  }

  .flashcard {
    height: clamp(280px, 48vh, 420px);
    min-height: 280px;
    max-height: 420px;
  }

  .card-actions {
    top: 10px;
    right: 10px;
    gap: 6px;
  }

  .card-action {
    width: 38px;
    height: 38px;
    font-size: 20px;
  }

  .card-inner,
  .card-face {
    height: 100%;
    min-height: 280px;
    max-height: 420px;
  }

  .definition {
    max-height: 260px;
  }

  .import-tabs {
    overflow-x: auto;
  }

  .import-tab {
    padding: 7px 12px;
    white-space: nowrap;
  }

  .wordbook-grid {
    grid-template-columns: 1fr;
  }
}

/* ── Dark mode ────────────────────────────────── */

/* 主题切换时，临时给所有元素叠加颜色过渡，避免影响日常 hover/focus 动效
   注意：不要把 background 这个 shorthand 放进来，否则它会和 @property
   gradient 变量插值打架，造成闪烁。只过渡 background-color 即可。 */
.theme-transitioning,
.theme-transitioning *,
.theme-transitioning *::before,
.theme-transitioning *::after {
  transition:
    background-color 0.32s ease,
    color 0.32s ease,
    border-color 0.32s ease,
    box-shadow 0.32s ease,
    fill 0.32s ease,
    stroke 0.32s ease,
    --body-grad-1 0.32s ease,
    --body-grad-2 0.32s ease,
    --scroll-thumb 0.32s ease,
    --scroll-track 0.32s ease !important;
}

[data-theme="dark"] {
  --bg: #1c1b18;
  --panel: #252420;
  --ink: #e8e3da;
  --muted: #8c8680;
  --line: #38342e;
  --shadow: 0 18px 44px rgba(0, 0, 0, 0.45);
  color-scheme: dark;
}

[data-theme="dark"] body {
  background:
    linear-gradient(180deg, rgba(255,255,255,0.03), rgba(255,255,255,0)),
    var(--bg);
}

[data-theme="dark"] .topbar,
[data-theme="dark"] .stats-strip,
[data-theme="dark"] .activity-panel,
[data-theme="dark"] .workspace,
[data-theme="dark"] .import-panel,
[data-theme="dark"] .memory-panel {
  background: rgba(37, 36, 32, 0.88);
}

[data-theme="dark"] .secondary-button,
[data-theme="dark"] .icon-button {
  background: #2e2c28;
  color: var(--ink);
}

[data-theme="dark"] .secondary-button:hover {
  background: #363330;
}

[data-theme="dark"] .close-import-btn {
  background: #2e2c28;
  color: var(--muted);
  border-color: var(--line);
}

[data-theme="dark"] .close-import-btn:hover {
  background: #363330;
  color: var(--ink);
  border-color: var(--muted);
}

[data-theme="dark"] .import-mode-card {
  background: #2a2820;
}

[data-theme="dark"] .activity-summary {
  background: var(--line);
}

[data-theme="dark"] .activity-summary div,
[data-theme="dark"] .wordbook-card {
  background: #2a2820;
}

[data-theme="dark"] .wordbook-card:hover:not(:disabled),
[data-theme="dark"] .wordbook-card:focus-visible {
  background: #1e2a26;
  border-color: rgba(36, 107, 97, 0.5);
}

[data-theme="dark"] .heatmap-cell {
  background: rgba(255, 255, 255, 0.07);
  border-color: rgba(255, 255, 255, 0.05);
}

[data-theme="dark"] .heatmap-cell.level-1 { background: rgba(49, 139, 125, 0.26); }
[data-theme="dark"] .heatmap-cell.level-2 { background: rgba(49, 139, 125, 0.42); }
[data-theme="dark"] .heatmap-cell.level-3 { background: rgba(49, 139, 125, 0.62); }
[data-theme="dark"] .heatmap-cell.level-4 { background: rgba(49, 139, 125, 0.86); }

[data-theme="dark"] .import-mode-append:hover {
  background: #1e2a22;
}

[data-theme="dark"] .import-mode-append:has(input:checked) {
  background: #1e2a22;
}

[data-theme="dark"] .import-mode-replace:hover {
  background: #2a1e1c;
}

[data-theme="dark"] .import-mode-replace:has(input:checked) {
  background: #2a1e1c;
}

[data-theme="dark"] .file-drop {
  background: #222018;
  color: var(--muted);
}

[data-theme="dark"] .file-drop:hover,
[data-theme="dark"] .file-drop.drag-over {
  background: #1e2a26;
}

[data-theme="dark"] .ai-convert-result-head {
  background: #2a2820;
}

[data-theme="dark"] .ai-convert-result textarea {
  background: #222018;
}

[data-theme="dark"] textarea,
[data-theme="dark"] select,
[data-theme="dark"] .search-input,
[data-theme="dark"] .ai-settings input,
[data-theme="dark"] .ai-convert-controls input[type="text"],
[data-theme="dark"] .memory-lookup input {
  background: #2e2c28;
  color: var(--ink);
  border-color: var(--line);
}

[data-theme="dark"] .overview {
  background: rgba(37, 36, 32, 0.72);
}

[data-theme="dark"] .word-item:hover,
[data-theme="dark"] .word-item.active {
  background: #2e2c28;
}

[data-theme="dark"] {
  --body-grad-1: rgba(28, 27, 24, 0.4);
  --body-grad-2: rgba(20, 19, 17, 0.6);
  --card-grad-1: rgba(45, 43, 38, 0.96);
  --card-grad-2: rgba(38, 36, 31, 0.99);
  --card-grad-base: #282520;
  --scroll-thumb: rgba(140, 132, 120, 0.32);
  --scroll-track: rgba(255, 255, 255, 0.03);
}

[data-theme="dark"] .rating {
  background: #2e2c28;
  border-color: rgba(110, 100, 88, 0.7);
}

[data-theme="dark"] .rating:disabled {
  background: #262420;
}

[data-theme="dark"] .rating.again {
  background: #34302a;
  border-color: rgba(170, 158, 140, 0.55);
}

[data-theme="dark"] .rating.again strong {
  color: #d8cdb9;
}

[data-theme="dark"] .rating.hard {
  background: #3a221c;
  border-color: rgba(230, 96, 78, 0.7);
}

[data-theme="dark"] .rating.hard strong {
  color: #f4a89a;
}

[data-theme="dark"] .rating.good {
  background: #3a2e12;
  border-color: rgba(232, 156, 48, 0.7);
}

[data-theme="dark"] .rating.good strong {
  color: #f3c87a;
}

[data-theme="dark"] .rating.easy {
  background: #1f3320;
  border-color: rgba(96, 180, 110, 0.7);
}

[data-theme="dark"] .rating.easy strong {
  color: #a9d9ad;
}

[data-theme="dark"] .rating.again:hover:not(:disabled) { background: #3f3a31; }
[data-theme="dark"] .rating.hard:hover:not(:disabled)  { background: #4a2922; }
[data-theme="dark"] .rating.good:hover:not(:disabled)  { background: #4a3a17; }
[data-theme="dark"] .rating.easy:hover:not(:disabled)  { background: #284029; }

[data-theme="dark"] .memory-panel {
  background:
    linear-gradient(135deg, rgba(36, 107, 97, 0.14), rgba(36, 107, 97, 0.05)),
    var(--panel);
  border-color: rgba(36, 107, 97, 0.32);
}

[data-theme="dark"] .memory-content {
  background: rgba(37, 36, 32, 0.85);
  border-color: rgba(36, 107, 97, 0.28);
}

[data-theme="dark"] .sentence-content {
  background: rgba(56, 103, 173, 0.09);
  border-color: rgba(56, 103, 173, 0.3);
}

[data-theme="dark"] .celebration {
  background:
    radial-gradient(circle at 50% -20%, rgba(47, 125, 71, 0.28), transparent 55%),
    linear-gradient(155deg, #1a2a1c, #1e1c14);
  border-color: rgba(47, 125, 71, 0.38);
}

[data-theme="dark"] .empty-state {
  background: rgba(37, 36, 32, 0.6);
  border-color: var(--line);
}

[data-theme="dark"] .overflow-menu-item:hover,
[data-theme="dark"] .overflow-menu-item:focus-visible {
  background: rgba(255, 255, 255, 0.07);
}

[data-theme="dark"] .overflow-menu-item.danger:hover,
[data-theme="dark"] .overflow-menu-item.danger:focus-visible {
  background: rgba(194, 65, 50, 0.15);
}

[data-theme="dark"] .undo-toast {
  background: var(--ink);
  color: var(--bg);
}

[data-theme="dark"] .undo-toast .text-button {
  color: var(--accent);
}

[data-theme="dark"] kbd {
  background: #2a2820;
  color: var(--muted);
  border-color: var(--line);
}

[data-theme="dark"] .progress-bar {
  background: rgba(36, 107, 97, 0.22);
}

[data-theme="dark"] .rating-row {
  background: rgba(37, 36, 32, 0.97);
  border-top-color: var(--line);
}

[data-theme="dark"] .definition {
  color: var(--ink);
}

[data-theme="dark"] .phonetic {
  color: var(--muted);
}