BOTTOM SHEET / POPOVER CARD
══════════════════════════════════ */
    #sheet-overlay {
      position: fixed;
      inset: 0;
      z-index: 80;
      display: none;
      /* Subtle dark overlay for both mobile and desktop */
      background: rgba(15, 18, 30, 0.45);
      opacity: 0;
      will-change: opacity;
      transition: opacity .3s;
    }

    #sheet-overlay.on {
      display: block;
      opacity: 1;
    }

    #bottom-sheet {
      position: fixed;
      left: 0;
      right: 0;
      bottom: 0;
      z-index: 90;
      will-change: transform, opacity;
      transform: translateY(110%);
      transition: transform .4s cubic-bezier(.32, .72, 0, 1), opacity .3s;
      padding-bottom: env(safe-area-inset-bottom, 0);
    }
    

    

    

    #bottom-sheet.open {
      transform: translateY(0);
    }

    #bs-inner {
      background: rgba(15, 18, 30, 0.85);
      border: 1px solid rgba(255, 255, 255, .1);
      border-bottom: none;
      border-radius: 32px 32px 0 0;
      overflow: hidden;
      backdrop-filter: blur(40px);
      -webkit-backdrop-filter: blur(40px);
      box-shadow: 0 -10px 40px rgba(0, 0, 0, 0.5);
      display: flex;
      flex-direction: column;
      max-height: calc(100vh - 60px);
      /* Leave safe area */
    }

    #bs-drag {
      width: 40px;
      height: 5px;
      border-radius: 3px;
      background: rgba(255, 255, 255, .2);
      margin: 12px auto 0;
      flex-shrink: 0;
    }

    /* ─── DESKTOP POPOVER MODE (>600px) ─── */
    @media (min-width: 601px) {
      #bottom-sheet {
        /* 摒弃跟随节点的绝对定位，改为固定在屏幕右侧的优雅侧边栏 */
        position: fixed;
        top: 24px;
        right: 12px;
        bottom: 24px;
        left: auto;
        width: 340px;
        
        /* 初始状态：靠右隐藏并稍微透明 */
        transform: translateX(120%);
        opacity: 0;
        pointer-events: none;
        
        /* 丝滑的滑出动画 */
        transition: transform .4s cubic-bezier(0.16, 1, 0.3, 1), opacity .3s ease;
        padding-bottom: 0;
        z-index: 100;
      }

      #bottom-sheet.open {
        transform: translateX(0);
        opacity: 1;
        pointer-events: auto;
      }

      #bs-inner {
        height: 100%; /* 撑满侧边栏高度 */
        border-radius: 24px;
        border: 1px solid rgba(255, 255, 255, 0.08);
        box-shadow: -10px 0 50px rgba(0, 0, 0, 0.5), inset 1px 0 0 rgba(255, 255, 255, 0.05);
        display: flex;
        flex-direction: column;
      }
      
      #bs-drag {
        display: none; /* 电脑端不需要顶部拖拽条 */
      }

      #bs-img-zone {
        height: 180px;
      }
    }

    /* Card image */
    #bs-img-zone {
      position: relative;
      height: 140px; /* 🌟 优化：从 180px 压缩到 120px，节约宝贵的纵向空间 */
      background: #0a0d1a;
      overflow: hidden;
      flex-shrink: 0;
      /* 🌟 核心魔法：透明度蒙版。让图片从上到下，由实心渐渐“消散”为完全透明 */
      -webkit-mask-image: linear-gradient(to bottom, #000 0%, #000 40%, transparent 100%);
      mask-image: linear-gradient(to bottom, #000 0%, #000 40%, transparent 100%);
    }

    #bs-img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      display: block;
      opacity: 0;
      transition: opacity 0.5s ease;
    }

    #bs-img.loaded {
      opacity: 1;
    }

    #bs-img-placeholder {
      position: absolute;
      inset: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 54px;
      opacity: .08;
      transition: opacity 0.4s ease;
      animation: placeholderBreathe 2.5s infinite ease-in-out;
    }
    @keyframes placeholderBreathe {
      0%, 100% { transform: scale(1); filter: brightness(1); }
      50% { transform: scale(1.08); filter: brightness(1.5); }
    }
    
    #bs-img-placeholder.fade-out {
      opacity: 0;
      animation: none;
    }

    

    /* ─── Header: word + pos (line 1), logic tag (line 2) ─── */
    #bs-header {
      padding: 0 20px 12px;
      flex-shrink: 0;
      border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    }

    #bs-header-row {
      position: relative;
      display: flex;
      align-items: baseline;
      gap: 10px;
      margin-top: -36px;
      z-index: 2;
    }

    #bs-word-big {
      font-family: var(--serif);
      font-size: 30px;
      font-weight: 700;
      color: #ffffff;
    }

    #bs-pos-tag {
      font-family: var(--mono);
      font-size: 11px;
      font-weight: 600;
      letter-spacing: .05em;
      flex-shrink: 0;
    }

    #bs-learned-badge {
      font-family: var(--mono);
      font-size: 9px;
      font-weight: 500;
      letter-spacing: .08em;
      padding: 2px 8px;
      border-radius: 8px;
      border: 1px solid;
      display: none;
      flex-shrink: 0;
      transition: opacity 0.5s ease;
    }

    /* ── 学完特效：星辉绽放 ── */
    .learned-burst {
      position: absolute;
      pointer-events: none;
      z-index: 100;
    }
    .learned-pulse {
      position: absolute;
      width: 20px; height: 20px;
      border-radius: 50%;
      transform: translate(-50%, -50%);
      animation: learnedPulse 0.7s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    }
    @keyframes learnedPulse {
      0%   { width: 20px; height: 20px; opacity: 0.6; }
      100% { width: 120px; height: 120px; opacity: 0; }
    }
    .learned-spark {
      position: absolute;
      width: 4px; height: 4px;
      border-radius: 50%;
      transform: translate(-50%, -50%);
      animation: learnedSpark 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    }
    @keyframes learnedSpark {
      0%   { opacity: 1; transform: translate(-50%, -50%) translate(0, 0) scale(1); }
      100% { opacity: 0; transform: translate(-50%, -50%) translate(var(--sx), var(--sy)) scale(0); }
    }

    #bs-logic-tag {
      font-family: var(--mono);
      font-size: 10px;
      letter-spacing: .06em;
      padding: 4px 10px;
      border-radius: 8px;
      font-weight: 600;
      line-height: 1.2;
      margin-top: 8px;
      display: inline-block;
    }

    /* ─── Card body ─── */
    #bs-body {
      padding: 16px 20px calc(24px + env(safe-area-inset-bottom));
      display: flex;
      flex-direction: column;
      gap: 14px;
      overflow-y: auto;
      overscroll-behavior: contain;
    }
    #bs-body::-webkit-scrollbar { width: 4px; }
    #bs-body::-webkit-scrollbar-track { background: transparent; }
    #bs-body::-webkit-scrollbar-thumb { background: rgba(255, 255, 255, 0.15); border-radius: 4px; }
    #bs-body::-webkit-scrollbar-thumb:hover { background: rgba(255, 255, 255, 0.3); }

    /* ─── Meaning row: left bar + meaning text + phonetic pill ─── */
    #bs-meaning-row {
      display: flex;
      align-items: flex-start;
      gap: 12px;
      padding-left: 12px;
      border-left-width: 3px;
      border-left-style: solid;
      border-radius: 0;
    }

    #bs-meaning {
      font-family: var(--serif);
      font-size: 15px;
      line-height: 1.6;
      font-weight: 500;
      color: rgba(255, 255, 255, 0.92);
      letter-spacing: 0.02em;
      flex: 1;
      min-width: 0;
    }

    #bs-phon-row {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 4px 12px 4px 10px;
      border-radius: 16px;
      cursor: pointer;
      transition: transform .15s, background .2s;
      user-select: none;
      -webkit-tap-highlight-color: transparent;
      flex-shrink: 0;
      margin-top: 1px;
    }
    #bs-phon-row:active { transform: scale(.95); }

    @keyframes sonarWave {
      0% { box-shadow: 0 0 0 0 var(--wave-color, rgba(255,255,255,0.4)); }
      100% { box-shadow: 0 0 0 16px rgba(0,0,0,0); }
    }
    #bs-phon-row.playing-audio {
      animation: sonarWave 1s cubic-bezier(0.25, 1, 0.5, 1) infinite;
    }

    #bs-phonetic { font-family: var(--mono); font-size: 12px; font-weight: 500; line-height: 1; }
    #bs-speak-icon { font-size: 13px; display: flex; align-items: center; justify-content: center; opacity: 0.8; }

    /* ─── 标签小标题 ─── */
    #bs-rel-label {
      font-family: var(--mono);
      font-size: 11px;
      letter-spacing: .2em; /* 🌟 拉开字距，更有极客设计感 */
      text-transform: uppercase;
      color: rgba(255, 255, 255, 0.4);
      /*margin-top: 4px;      和上面的释义拉开一点呼吸空间 */
      margin-bottom: -4px; /* 和下面的笔记卡片紧凑贴合 */
    }


    /* ─── 详细笔记卡片 (Notes) ─── */
    .notes-card {
      font-family: var(--serif);
      font-size: 14px;
      line-height: 1.8; /* 🌟 核心优化：1.8 的超大行高，拯救长文阅读疲劳 */
      letter-spacing: 0.03em;
      color: rgba(255, 255, 255, 0.75); /* 柔和的次级文字颜色，不刺眼 */
      padding: 16px 18px;
      background: rgba(10, 14, 28, 0.4); /* 和 Tooltip 呼应的深渊蓝底色 */
      border: 1px solid rgba(255, 255, 255, 0.05);
      border-radius: 12px;
      width: 100%;
      white-space: pre-wrap; /* 完美保留你数据里的换行符 */
      box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.2);
    }