/* --- 1. 基础设置 --- */
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
      /* 专业字体栈: 英文优先 + 中文补充 */
      font-family:
        "Inter", "SF Pro Display", "Segoe UI", system-ui,
        /* 英文优先 */
        "PingFang SC", "Microsoft YaHei", "Noto Sans SC",
        /* 中文补充 */
        -apple-system, BlinkMacSystemFont, sans-serif;
      -webkit-tap-highlight-color: transparent;
      /* 文本渲染优化 */
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
      text-rendering: optimizeLegibility;
    }

    body {
      background-color: #FDF6E3;
      color: #2C3E50;
      min-height: 100vh;
      padding: 20px;
      display: flex;
      flex-direction: column;
      align-items: center;
      transition: background-color 0.8s cubic-bezier(0.2, 0.8, 0.2, 1), color 0.5s ease;
      overflow-x: hidden;
      overscroll-behavior: none;
    }

    /* --- 2. 极致沉浸模式 --- */
    body.idle-mode {
      cursor: none;
    }

    body.idle-mode .header,
    body.idle-mode .header.visible,
    body.idle-mode .controls,
    body.idle-mode .controls.visible,
    body.idle-mode .nav-bar,
    body.idle-mode .action-btn,
    body.idle-mode .upload-section,
    body.idle-mode .deck-history {
      opacity: 0 !important;
      pointer-events: none !important;
      transform: translateY(10px);
      filter: blur(5px);
    }

    body.idle-mode .card-container {
      transform: scale(1.02);
      transition: transform 1s ease;
      filter: drop-shadow(0 20px 50px rgba(0, 0, 0, 0.15));
    }

    body.focus-mode {
      background-color: #1a1a1a;
      color: #ecf0f1;
    }

    .header,
    .controls,
    .nav-bar,
    .action-btn,
    .upload-section,
    .deck-history {
      transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1), filter 0.8s ease;
    }

    /* --- 3. 按钮样式 --- */
    .top-btn {
      background: white;
      border: 2px solid #EEE;
      cursor: pointer;
      color: #7F8C8D;
      padding: 10px;
      border-radius: 50%;
      transition: 0.2s;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 4px 0 #eee;
      transform: translateY(0);
    }

    .top-btn:active {
      transform: translateY(4px);
      box-shadow: 0 0 0 #eee;
    }

    .top-btn:hover {
      border-color: #3498DB;
      color: #3498DB;
    }

    .top-btn.active {
      color: #3498DB;
      border-color: #3498DB;
    }

    .top-btn.playing {
      color: #2ECC71;
      border-color: #2ECC71;
    }

    .top-btn.camera-on {
      color: #E74C3C;
      border-color: #E74C3C;
    }

    .top-btn.loading {
      cursor: wait;
    }

    body.focus-mode .top-btn {
      background: #333;
      border-color: #444;
      color: #aaa;
      box-shadow: 0 4px 0 #222;
    }

    body.focus-mode .top-btn:active {
      box-shadow: 0 0 0 #222;
    }

    body.focus-mode .top-btn:hover {
      color: #fff;
      border-color: #555;
    }

    @keyframes spin {
      100% {
        transform: rotate(360deg);
      }
    }

    /* --- 4. 布局结构 --- */
    .container {
      width: 100%;
      max-width: 800px;
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
      z-index: 10;
      flex: 1;
    }

    .header {
      width: 100%;
      display: flex;
      justify-content: flex-end;
      align-items: center;
      margin-bottom: 20px;
      height: 50px;
      position: relative;
      z-index: 20;
      gap: 12px;
      opacity: 0;
      transition: opacity 1s;
      pointer-events: none;
    }

    .header.visible {
      opacity: 1;
      pointer-events: auto;
    }

    .upload-section {
      background: white;
      padding: 40px 20px;
      border-radius: 30px;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
      text-align: center;
      margin-top: 40px;
      width: 100%;
      max-width: 500px;
      border: 4px solid #fff;
    }

    .upload-btn {
      display: inline-block;
      padding: 12px 30px;
      background: #2ECC71;
      color: white;
      border-radius: 50px;
      cursor: pointer;
      font-size: 16px;
      margin-top: 20px;
      font-weight: 700;
      box-shadow: 0 6px 0 #27AE60;
      transition: transform 0.1s;
    }

    .upload-btn:active {
      transform: translateY(6px);
      box-shadow: none;
    }

    #file-input {
      display: none;
    }

    /* 历史记录列表样式 */
    .deck-history {
      width: 100%;
      max-width: 500px;
      margin-top: 20px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .history-item {
      background: rgba(255, 255, 255, 0.6);
      padding: 15px;
      border-radius: 15px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      border: 1px solid rgba(0, 0, 0, 0.05);
      transition: 0.2s;
    }

    .history-item.due {
      background: #fff;
      border-left: 5px solid #E74C3C;
      box-shadow: 0 5px 15px rgba(231, 76, 60, 0.15);
    }

    .history-info h4 {
      font-size: 14px;
      color: #2C3E50;
      margin-bottom: 4px;
    }

    .history-info p {
      font-size: 12px;
      color: #7F8C8D;
    }

    .history-tag {
      font-size: 10px;
      padding: 4px 8px;
      border-radius: 10px;
      background: #eee;
      color: #999;
      font-weight: bold;
    }

    .history-item.due .history-tag {
      background: #FDEDEC;
      color: #E74C3C;
    }

    .card-section {
      display: none;
      width: 100%;
      flex-direction: column;
      align-items: center;
      flex: 1;
      justify-content: center;
    }

    /* --- 5. 卡片样式 --- */
    .card-container {
      perspective: 1500px;
      width: 100%;
      max-width: 800px;
      /* 增大卡片宽度以容纳图文 */
      aspect-ratio: 3/2;
      margin-bottom: 30px;
      position: relative;
      transition: all 0.5s ease;
    }

    @media (max-width: 600px) {
      .card-container {
        aspect-ratio: 4/5;
        max-height: 55vh;
        width: 95%;
        margin-bottom: 20px;
      }

      .header {
        justify-content: center;
      }
    }

    .card {
      width: 100%;
      height: 100%;
      position: relative;
      transform-style: preserve-3d;
      transition: transform 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
      cursor: pointer;
    }

    .card.flipped {
      transform: rotateY(180deg);
    }

    .card-face {
      position: absolute;
      width: 100%;
      height: 100%;
      backface-visibility: hidden;
      -webkit-backface-visibility: hidden;
      border-radius: 30px;
      padding: 30px;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      align-items: center;
      box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1), 0 5px 15px rgba(0, 0, 0, 0.05);
      border: 4px solid #fff;
      overflow: hidden;
      transition: all 0.3s ease;
    }

    .card-front {
      background: #ffffff;
    }

    .card-back {
      background: #F0F3F4;
      transform: rotateY(180deg);
      border-color: #BDC3C7;
      color: #2C3E50;
    }

    body.focus-mode .card-front {
      background: #2c3e50;
      border-color: #34495e;
      color: #ecf0f1;
    }

    body.focus-mode .card-back {
      background: #34495e;
      border-color: #2c3e50;
      color: #ecf0f1;
    }

    .card-label {
      font-size: 12px;
      text-transform: uppercase;
      letter-spacing: 2px;
      font-weight: 800;
      padding: 6px 16px;
      border-radius: 20px;
      margin-bottom: 10px;
      z-index: 2;
      flex-shrink: 0;
    }

    .card-front .card-label {
      background: #E8F6F3;
      color: #16A085;
    }

    .card-back .card-label {
      background: #EAF2F8;
      color: #2980B9;
    }

    /* 普通掌握状态 */
    .card.mastered .card-front {
      border-color: #2ECC71;
      background: #EAFAF1;
    }

    .card.mastered .card-front .card-label {
      background: #D5F5E3;
      color: #27AE60;
    }

    /* 长期记忆状态 (Level 5+) */
    .card.long-term .card-front {
      border-color: #145A32;
      background: #E9F7EF;
    }

    .card.long-term .card-front .card-label {
      background: #145A32;
      color: #A9DFBF;
      content: "长期记忆";
    }

    body.focus-mode .card.mastered .card-front {
      background: #145A32;
      border-color: #27AE60;
    }

    body.focus-mode .card.long-term .card-front {
      background: #0B5345;
      border-color: #1E8449;
    }

    .card-content {
      /* 响应式字体大小: 最小20px，最夤28px，基于视口缩放 */
      font-size: clamp(20px, 2.5vw + 0.5rem, 28px);
      line-height: 1.7;
      letter-spacing: 0.02em;
      width: 100%;
      flex: 1;
      display: flex;
      flex-direction: column;
      min-height: 0;
      overflow: hidden;
      /* 用户要求无滚动条 */
      padding: 15px 0;
      align-items: center;
      justify-content: center;
      /* 文本计算优化 */
      word-break: break-word;
      hyphens: auto;
    }

    .card-content.full-image-mode {
      padding: 0;
    }

    .card-image {
      flex: 0 1 auto;
      width: auto;
      max-width: 100%;
      max-height: 70%;
      min-height: 0;
      border-radius: 12px;
      margin-bottom: 15px;
      object-fit: contain;
      box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    }

    .card-content.full-image-mode .card-image {
      max-height: 100%;
      width: 100%;
      height: 100%;
      flex: 1;
      margin: 0;
      border-radius: 20px;
      box-shadow: none;
    }

    .card-text-wrapper {
      flex: 0 0 auto;
      width: 100%;
      max-width: 60ch;
      /* 最佳阅读宽度: 60字符 */
      white-space: pre-wrap;
      word-wrap: break-word;
      text-align: center;
      font-weight: 500;
      margin: 0 auto;
      /* 中英文混排优化 */
      word-spacing: 0.05em;
    }

    .card-text-wrapper.long-text {
      text-align: left;
      font-size: clamp(16px, 2vw + 0.25rem, 22px);
      line-height: 1.8;
    }

    /* 英文单词/词组专用样式 - 响应式大字号显示 */
    .card-text-wrapper.english-word {
      font-size: clamp(36px, 6vw + 1rem, 64px);
      font-weight: 700;
      color: #2C3E50;
      text-transform: capitalize;
      letter-spacing: 0.02em;
      font-family: "Inter", "SF Pro Display", system-ui, sans-serif;
    }

    body.focus-mode .card-text-wrapper.english-word {
      color: #ecf0f1;
    }

    @media (max-width: 600px) {
      .card-text-wrapper.english-word {
        font-size: 42px;
      }
    }

    .card-hint {
      font-size: 12px;
      color: #BDC3C7;
      margin-top: 10px;
      opacity: 0;
      transition: opacity 0.5s;
      font-weight: bold;
    }

    .card-face:hover .card-hint {
      opacity: 0.8;
    }

    /* --- 6. 底部控制栏 --- */
    .controls {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 20px;
      flex-wrap: wrap;
      margin-bottom: 20px;
      width: 100%;
      max-width: 500px;
      z-index: 20;
      opacity: 0;
      transition: opacity 1s;
      pointer-events: none;
    }

    .controls.visible {
      opacity: 1;
      pointer-events: auto;
    }

    .nav-bar {
      background: white;
      border-radius: 60px;
      padding: 8px;
      display: flex;
      align-items: center;
      box-shadow: 0 10px 20px rgba(0, 0, 0, 0.05);
      border: 1px solid #eee;
    }

    body.focus-mode .nav-bar {
      background: #333;
      border-color: #444;
    }

    .nav-btn {
      width: 45px;
      height: 45px;
      border-radius: 50%;
      border: none;
      background: transparent;
      cursor: pointer;
      color: #7F8C8D;
      transition: 0.2s;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .nav-btn:hover {
      background-color: #F7F9F9;
      color: #3498DB;
    }

    body.focus-mode .nav-btn:hover {
      background-color: #444;
      color: #fff;
    }

    .progress-text {
      padding: 0 20px;
      font-size: 16px;
      font-weight: 700;
      color: #7F8C8D;
      text-align: center;
      min-width: 100px;
    }

    .progress-sub {
      font-size: 11px;
      color: #BDC3C7;
      display: block;
      font-weight: normal;
      margin-top: 2px;
    }

    .action-btn {
      padding: 12px 24px;
      border-radius: 50px;
      border: none;
      background: white;
      color: #7F8C8D;
      font-weight: 700;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 15px;
      box-shadow: 0 6px 0 #eee;
      transform: translateY(0);
      transition: 0.1s;
      border: 1px solid #eee;
    }

    .action-btn:active {
      transform: translateY(6px);
      box-shadow: 0 0 0 #eee;
    }

    .action-btn.primary {
      background: #2ECC71;
      color: white;
      box-shadow: 0 6px 0 #27AE60;
      border-color: #2ECC71;
    }

    .action-btn.primary:active {
      box-shadow: 0 0 0 #27AE60;
    }

    body.focus-mode .action-btn {
      background: #333;
      color: #aaa;
      box-shadow: 0 6px 0 #222;
      border-color: #444;
    }

    body.focus-mode .action-btn.primary {
      background: #219150;
      box-shadow: 0 6px 0 #145A32;
      border-color: #219150;
      color: #fff;
    }

    /* --- 7. 模态框与组件 --- */
    .modal-overlay {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(0, 0, 0, 0.5);
      z-index: 1000;
      display: none;
      justify-content: center;
      align-items: center;
      backdrop-filter: blur(5px);
    }

    .modal-content {
      background: white;
      width: 90%;
      max-width: 400px;
      border-radius: 30px;
      padding: 30px;
      box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
      text-align: center;
      animation: modalPop 0.3s ease-out;
    }

    @keyframes modalPop {
      from {
        transform: scale(0.95);
        opacity: 0;
      }

      to {
        transform: scale(1);
        opacity: 1;
      }
    }

    .modal-title {
      font-size: 22px;
      margin-bottom: 20px;
      color: #2C3E50;
      font-weight: 800;
      font-family: "Comic Sans MS", sans-serif;
    }

    .modal-btn {
      background: #3498DB;
      color: white;
      border: none;
      padding: 12px 30px;
      border-radius: 50px;
      font-size: 15px;
      font-weight: bold;
      cursor: pointer;
      transition: 0.2s;
      width: 100%;
      box-shadow: 0 6px 0 #2980B9;
      margin-top: 10px;
    }

    .modal-btn.danger {
      background: #E74C3C;
      box-shadow: 0 6px 0 #C0392B;
      margin-top: 20px;
    }

    .modal-btn:hover {
      transform: translateY(-2px);
    }

    .modal-btn:active {
      transform: translateY(4px);
      box-shadow: none;
    }

    #gesture-feedback {
      position: fixed;
      top: 50%;
      left: 50%;
      width: 140px;
      height: 140px;
      border-radius: 50%;
      --c: #2ECC71;
      background: conic-gradient(var(--c) var(--p, 0%), rgba(255, 255, 255, 0.1) 0deg);
      -webkit-mask: radial-gradient(transparent 60%, black 61%);
      mask: radial-gradient(transparent 60%, black 61%);
      pointer-events: none;
      z-index: 5000;
      opacity: 0;
      transform: translate(-50%, -50%) scale(0.9);
      transition: transform 0.1s linear, opacity 0.2s ease;
    }

    #gesture-feedback.show {
      opacity: 0.8;
      transform: translate(-50%, -50%) scale(1);
      filter: drop-shadow(0 0 10px var(--c));
    }

    #gesture-feedback.type-ok {
      --c: #2ECC71;
    }

    #gesture-feedback.type-palms {
      --c: #3498DB;
    }

    .toast {
      visibility: hidden;
      min-width: 250px;
      background-color: #333;
      color: #fff;
      text-align: center;
      border-radius: 50px;
      padding: 16px;
      position: fixed;
      z-index: 6000;
      left: 50%;
      bottom: 30px;
      transform: translateX(-50%);
      font-size: 14px;
      opacity: 0;
      transition: 0.3s;
      box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
      font-weight: bold;
    }

    .toast.show {
      visibility: visible;
      opacity: 1;
      bottom: 50px;
    }

    .settings-group {
      margin-bottom: 24px;
      text-align: left;
    }

    .settings-label {
      display: block;
      font-weight: 700;
      margin-bottom: 10px;
      color: #2C3E50;
      font-size: 14px;
    }

    .settings-options {
      display: flex;
      gap: 10px;
      background: #F0F3F4;
      padding: 6px;
      border-radius: 16px;
    }

    .settings-option {
      flex: 1;
      text-align: center;
      padding: 10px;
      border-radius: 12px;
      cursor: pointer;
      font-size: 13px;
      color: #7F8C8D;
      transition: all 0.2s;
      font-weight: 600;
    }

    .settings-option.selected {
      background: white;
      color: #2ECC71;
      box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
    }

    .range-slider {
      flex: 1;
      accent-color: #2ECC71;
      height: 6px;
      background: #eee;
      border-radius: 3px;
      width: 100%;
    }

    .switch {
      position: relative;
      display: inline-block;
      width: 50px;
      height: 28px;
    }

    .switch input {
      opacity: 0;
      width: 0;
      height: 0;
    }

    .slider {
      position: absolute;
      cursor: pointer;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background-color: #ccc;
      transition: .4s;
      border-radius: 34px;
    }

    .slider:before {
      position: absolute;
      content: "";
      height: 20px;
      width: 20px;
      left: 4px;
      bottom: 4px;
      background-color: white;
      transition: .4s;
      border-radius: 50%;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    }

    input:checked+.slider {
      background-color: #2ECC71;
    }

    input:checked+.slider:before {
      transform: translateX(22px);
    }

    body.autoplay-mode .card-container {
      perspective: none;
    }

    body.autoplay-mode .card {
      transform: none !important;
      transition: none;
    }

    body.autoplay-mode .card-face {
      transition: opacity 0.4s ease;
      transform: none !important;
      backface-visibility: visible;
      top: 0;
      left: 0;
    }

    body.autoplay-mode .card-front {
      opacity: 1;
      z-index: 1;
    }

    body.autoplay-mode .card-back {
      opacity: 0;
      z-index: 2;
      transform: none !important;
      background: #F0F3F4;
    }

    body.autoplay-mode .card.flipped .card-back {
      opacity: 1;
    }

    .no-transition,
    .no-transition * {
      transition: none !important;
    }

    #flow-start-screen {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background-color: #1a1a1a;
      z-index: 2500;
      display: none;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      color: #ecf0f1;
      text-align: center;
      opacity: 0;
      transition: opacity 0.8s ease;
    }

    #flow-start-screen.active {
      display: flex;
      opacity: 1;
    }

    /* 梦幻辉光效果 */
    .dream-glow {
      animation: dreamGlow 3s ease-in-out infinite;
    }

    @keyframes dreamGlow {
      0%, 100% {
        text-shadow:
          0 0 10px rgba(255, 255, 255, 0.5),
          0 0 20px rgba(255, 255, 255, 0.3),
          0 0 30px rgba(255, 255, 255, 0.1);
      }
      50% {
        text-shadow:
          0 0 15px rgba(255, 255, 255, 0.8),
          0 0 30px rgba(255, 255, 255, 0.5),
          0 0 50px rgba(255, 255, 255, 0.3),
          0 0 80px rgba(255, 255, 255, 0.1);
      }
    }

    .flow-title {
      animation: dreamGlow 4s ease-in-out infinite;
    }

    .breathing-circle {
      animation: dreamGlowCircle 4s ease-in-out infinite, breathe 12s ease-in-out infinite;
    }

    @keyframes dreamGlowCircle {
      0%, 100% {
        box-shadow:
          0 0 20px rgba(46, 204, 113, 0.3),
          0 0 40px rgba(46, 204, 113, 0.2),
          0 0 60px rgba(46, 204, 113, 0.1);
      }
      50% {
        box-shadow:
          0 0 30px rgba(46, 204, 113, 0.5),
          0 0 60px rgba(46, 204, 113, 0.3),
          0 0 100px rgba(46, 204, 113, 0.2);
      }
    }

    .start-flow-btn {
      animation: btnGlow 2s ease-in-out infinite;
    }

    @keyframes btnGlow {
      0%, 100% {
        box-shadow: 0 6px 0 #27AE60, 0 0 15px rgba(46, 204, 113, 0.3);
      }
      50% {
        box-shadow: 0 6px 0 #27AE60, 0 0 30px rgba(46, 204, 113, 0.6), 0 0 50px rgba(46, 204, 113, 0.3);
      }
    }

    .breathing-circle {
      width: 100px;
      height: 100px;
      border-radius: 50%;
      border: 4px solid rgba(46, 204, 113, 0.2);
      margin-bottom: 40px;
      animation: breathe 12s ease-in-out infinite;
      position: relative;
    }

    .breathing-circle::after {
      content: '';
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      width: 16px;
      height: 16px;
      background: #2ECC71;
      border-radius: 50%;
      box-shadow: 0 0 20px #2ECC71;
    }

    @keyframes breathe {

      0%,
      100% {
        transform: scale(1);
        border-color: rgba(46, 204, 113, 0.2);
      }

      50% {
        transform: scale(1.5);
        border-color: rgba(46, 204, 113, 0.5);
      }
    }

    .start-flow-btn {
      background: transparent;
      color: #2ECC71;
      border: 2px solid #333;
      padding: 12px 40px;
      border-radius: 50px;
      font-size: 16px;
      letter-spacing: 1px;
      cursor: pointer;
      transition: all 0.4s ease;
      font-weight: bold;
    }

    .start-flow-btn:hover {
      border-color: #2ECC71;
      background: rgba(46, 204, 113, 0.1);
      transform: translateY(-2px);
    }

    #celebration-overlay {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(255, 255, 255, 0.95);
      z-index: 2000;
      display: none;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      text-align: center;
    }

    .confetti {
      position: absolute;
      width: 8px;
      height: 8px;
      background-color: #f2d74e;
      animation: fall linear forwards;
    }

    @keyframes fall {
      to {
        transform: translateY(100vh) rotate(720deg);
      }
    }

    #input_video {
      position: absolute;
      top: -9999px;
      left: 0;
      width: 32px;
      height: 32px;
      opacity: 0;
      pointer-events: none;
    }

    .calibration-video-container {
      width: 100%;
      height: 200px;
      background: #000;
      border-radius: 20px;
      overflow: hidden;
      margin-bottom: 20px;
      position: relative;
      border: 4px solid #eee;
    }

    .calibration-video-container canvas {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transform: scaleX(-1);
    }

    .calibration-status {
      position: absolute;
      bottom: 10px;
      left: 0;
      width: 100%;
      text-align: center;
      color: white;
      font-size: 12px;
      background: rgba(0, 0, 0, 0.5);
      padding: 4px 0;
    }

    #review-modal .modal-content {
      border: 2px solid #F1C40F;
    }

    #review-modal .modal-title {
      color: #F39C12;
    }

    .review-count {
      font-size: 40px;
      color: #E67E22;
      font-weight: bold;
      margin: 10px 0;
    }
/* --- Page Flip Animation --- */
@keyframes slideOutLeft {
    to { transform: translateX(-120%) rotate(-5deg); opacity: 0.5; }
}
@keyframes slideInRight {
    from { transform: translateX(120%) rotate(5deg); opacity: 0.5; }
    to { transform: translateX(0) rotate(0); opacity: 1; }
}
@keyframes slideOutRight {
    to { transform: translateX(120%) rotate(5deg); opacity: 0.5; }
}
@keyframes slideInLeft {
    from { transform: translateX(-120%) rotate(-5deg); opacity: 0.5; }
    to { transform: translateX(0) rotate(0); opacity: 1; }
}

.card-container.anim-out-left { animation: slideOutLeft 0.3s ease-in forwards; }
.card-container.anim-in-right { animation: slideInRight 0.3s ease-out forwards; }
.card-container.anim-out-right { animation: slideOutRight 0.3s ease-in forwards; }
.card-container.anim-in-left { animation: slideInLeft 0.3s ease-out forwards; }

/* --- 摄像头预览窗口 --- */
#camera-preview {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 160px;
    height: 120px;
    background: rgba(0, 0, 0, 0.7);
    border-radius: 12px;
    overflow: hidden;
    z-index: 100;
    display: none;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    border: 2px solid rgba(255, 255, 255, 0.2);
}

#camera-preview.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

#preview-video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transform: scaleX(-1);
}

.preview-toggle-btn {
    position: absolute;
    top: 4px;
    right: 4px;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: none;
    background: rgba(0, 0, 0, 0.5);
    color: white;
    font-size: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background 0.2s;
}

.preview-toggle-btn:hover {
    background: rgba(0, 0, 0, 0.7);
}

/* --- 手势状态指示器 --- */
#gesture-status {
    position: fixed;
    bottom: 210px;
    right: 20px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 8px 14px;
    border-radius: 20px;
    font-size: 13px;
    z-index: 100;
    display: none;
    align-items: center;
    gap: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    transition: all 0.2s ease;
}

#gesture-status.show {
    display: flex;
    animation: fadeIn 0.2s ease;
}

#gesture-status.active-ok {
    background: rgba(46, 204, 113, 0.9);
}

#gesture-status.active-palms {
    background: rgba(52, 152, 219, 0.9);
}

#gesture-icon {
    font-size: 16px;
}

#gesture-text {
    font-weight: 500;
}

/* --- 手势提示条 --- */
#gesture-hint-bar {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-top: 1px solid rgba(0, 0, 0, 0.1);
    padding: 12px 20px;
    z-index: 50;
    display: none;
    justify-content: center;
    align-items: center;
    gap: 30px;
    font-size: 13px;
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
}

#gesture-hint-bar.show {
    display: flex;
}

.hint-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #555;
}

.hint-emoji {
    font-size: 18px;
}

.hint-label {
    font-weight: 600;
    color: #2C3E50;
}

.hint-key {
    font-size: 11px;
    color: #95a5a6;
    background: #f0f0f0;
    padding: 2px 8px;
    border-radius: 10px;
}

.hint-divider {
    color: #ddd;
    font-size: 18px;
}

body.focus-mode #gesture-hint-bar {
    background: rgba(30, 30, 30, 0.95);
    border-top-color: rgba(255, 255, 255, 0.1);
}

body.focus-mode .hint-item {
    color: #aaa;
}

body.focus-mode .hint-label {
    color: #ddd;
}

body.focus-mode .hint-key {
    background: #333;
    color: #888;
}

body.focus-mode .hint-divider {
    color: #444;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* 隐藏状态下的手势提示条 */
body.idle-mode #gesture-hint-bar,
body.idle-mode #camera-preview,
body.idle-mode #gesture-status {
    opacity: 0;
    pointer-events: none;
}

/* --- 8. 移动端图标适配 --- */
@media (max-width: 600px) {
  /* 顶栏按钮图标放大 */
  .top-btn {
    padding: 12px;
  }

  .top-btn svg {
    width: 28px !important;
    height: 28px !important;
  }

  /* 导航按钮图标放大 */
  .nav-btn {
    width: 52px;
    height: 52px;
  }

  .nav-btn svg {
    width: 28px;
    height: 28px;
  }

  /* 操作按钮图标大小适配 */
  .action-btn svg {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
  }

  /* 手势提示条图标放大 */
  .hint-emoji {
    font-size: 22px;
  }

  /* 全屏提示按钮适配手机 */
  #fullscreen-hint-btn {
    font-size: 13px;
    padding: 8px 20px;
    top: 10%;
  }

  /* 摄像头预览窗口缩小适配手机 */
  #camera-preview {
    width: 120px;
    height: 90px;
    bottom: 70px;
    right: 12px;
  }

  /* 手势状态指示器适配手机 */
  #gesture-status {
    bottom: 175px;
    right: 12px;
    font-size: 12px;
    padding: 6px 12px;
  }

  #gesture-icon {
    font-size: 14px;
  }

  /* Toast提示在手机底部居中 */
  .toast {
    left: 50%;
    right: auto;
    transform: translateX(-50%);
    min-width: 200px;
    font-size: 13px;
  }

  .toast.show {
    bottom: 40px;
  }
}

/* 进一步适配超小屏幕 */
@media (max-width: 380px) {
  .top-btn svg {
    width: 24px !important;
    height: 24px !important;
  }

  .top-btn {
    padding: 10px;
  }
}