/* ── 汉堡菜单按钮（默认隐藏，窄屏显示）──── */
    .menu-btn {
      display: none;
      width: 32px;
      height: 32px;
      border-radius: 8px;
      background: var(--panel);
      border: 1px solid var(--border);
      color: var(--fg-dim);
      cursor: pointer;
      align-items: center;
      justify-content: center;
      flex-shrink: 0;
    }
    .menu-btn svg {
      width: 20px;
      height: 20px;
      stroke: currentColor;
      fill: none;
      stroke-width: 2;
      stroke-linecap: round;
    }
    .sidebar-overlay {
      display: none;
      position: fixed;
      inset: 0;
      background: rgba(0, 0, 0, 0.6);
      z-index: 40;
      backdrop-filter: blur(2px);
      opacity: 0;
      transition: opacity 0.2s ease;
    }
    .sidebar-overlay.show {
      display: block;
      opacity: 1;
    }
    .sidebar-close {
      display: none;
      margin-left: auto;
      width: 32px;
      height: 32px;
      border-radius: 8px;
      background: transparent;
      border: none;
      color: var(--fg-dim);
      font-size: var(--fs-18);
      cursor: pointer;
      line-height: 1;
    }
    .sidebar-close:hover { background: var(--bg-soft); color: var(--fg); }

    /* ── 平板 ≤ 960px ─────────────────── */
    @media (max-width: 960px) {
      .hero-card { padding: 24px 20px; }
      .hero-card h2 { font-size: 28px; }
      .hero-card p { font-size: var(--fs-14); }
      .examples { display: flex; flex-direction: column; align-items: center; }
      .example { max-width: 100%; min-width: auto; }
      .msg-wrap { padding: 0 18px; }
      .composer-wrap { padding: 12px 18px 20px; }
      .topbar { padding: 10px 18px; }
      .composer { border-radius: var(--radius); }
      .bubble.user { max-width: 88%; }
    }

    /* ── 手机 ≤ 720px：侧栏变抽屉 ────────── */
    @media (max-width: 720px) {
      aside {
        position: fixed;
        top: 0;
        left: 0;
        bottom: 0;
        width: 82vw;
        max-width: 320px;
        z-index: 50;
        transform: translateX(-100%);
        transition: transform 0.25s ease;
        box-shadow: 4px 0 24px rgba(0, 0, 0, 0.4);
      }
      aside.open { transform: translateX(0); }
      .sidebar-close { display: flex; align-items: center; justify-content: center; }
      .menu-btn { display: inline-flex; }

      main { width: 100%; }
      .topbar {
        padding: 10px 14px;
        gap: 8px;
      }
      .model-badge {
        font-size: 12px;
        padding: 5px 10px;
      }
      .status {
        display: none;
      }
      .status.busy, .status.err {
        display: inline-block;
        margin-left: auto;
        font-size: var(--fs-11);
        padding: 4px 8px;
      }

      .hero-card {
        padding: 20px 16px;
        border-radius: var(--radius);
      }
      .hero-card h2 { font-size: 24px; }
      .hero-card p { font-size: var(--fs-14); }
      .hero-card .eyebrow { font-size: var(--fs-11); }
      .empty-state { margin-top: 8px; padding: 0 14px; }

      .bubble {
        padding: 12px 14px;
        border-radius: var(--radius);
        font-size: var(--fs-14);
        margin-bottom: 10px;
      }
      .bubble.user { max-width: 90%; }
      .bubble .content { font-size: var(--fs-14); line-height: 1.6; }
      .bubble .content pre {
        font-size: var(--fs-12);
        padding: 10px 12px;
      }

      .msg-wrap { padding: 0 14px; }
      .composer-wrap { padding: 8px 14px 16px; }
      .composer textarea {
        padding: 10px 0 0;
        min-height: 44px;
        font-size: var(--fs-15); /* 防止 iOS 聚焦自动放大 */
      }
      .icon-btn, .send-btn { width: 34px; height: 34px; }
      .composer-hint { font-size: 11px; margin-top: 6px; }

      .attachments { padding: 10px 12px 0; gap: 6px; }
      .chip { max-width: 100%; }
      .chip .chip-name { max-width: 140px; }

      .tool-summary { max-width: 160px; font-size: var(--fs-12); }
      .tool-body { font-size: var(--fs-12); padding: 10px 12px; }

      .theme-toggle { width: 34px; height: 34px; }
    }

    /* ── 超窄 ≤ 380px ────────────────── */
    @media (max-width: 380px) {
      .hero-card h2 { font-size: 20px; }
      .hero-card p { font-size: var(--fs-13); }
      .model-badge { padding: 5px 8px; font-size: 11px; }
      .bubble.user { max-width: 94%; }
      .topbar { padding: 8px 12px; gap: 6px; }
      .examples { display: none; }
    }