.side-toolbar {
    position: fixed; right: 16px; bottom: 80px; z-index: 999;
    display: flex; flex-direction: column; gap: 12px; align-items: flex-end;
  }
  .side-toolbar a {
    display: flex; align-items: center; justify-content: center;
    width: 52px; height: 52px; border-radius: 50%;
    box-shadow: 0 2px 12px rgba(0,0,0,.15);
    transition: transform .25s, box-shadow .25s;
    position: relative;
  }
  .side-toolbar a:hover {
    transform: scale(1.12); box-shadow: 0 4px 20px rgba(0,0,0,.25);
  }
  /* tooltip 提示文字 */
  .side-toolbar a .tip {
    position: absolute; right: 62px; top: 50%; transform: translateY(-50%);
    background: #333; color: #fff; padding: 6px 14px; border-radius: 6px;
    font-size: 13px; white-space: nowrap;
    opacity: 0; pointer-events: none; transition: opacity .2s;
  }
  .side-toolbar a:hover .tip { opacity: 1; }
  .side-toolbar a .tip::after {
    content: ""; position: absolute; right: -6px; top: 50%; transform: translateY(-50%);
    border: 6px solid transparent; border-left-color: #333; border-right: none;
  }

  /* WhatsApp 按钮 */
  .btn-whatsapp { background: #25D366; }
  .btn-whatsapp svg { fill: #fff; width: 28px; height: 28px; }

  /* Facebook Messenger 按钮 */
  .btn-messenger { background: #0084FF; }
  .btn-messenger svg { fill: #fff; width: 26px; height: 26px; }

  /* TikTok 按钮 */
  .btn-tiktok { background: #000; }
  .btn-tiktok svg { fill: #fff; width: 24px; height: 24px; }

  /* 返回顶部按钮 */
  .btn-backtop {
    background: #1a73e8; opacity: 0; pointer-events: none;
    transition: opacity .3s, transform .25s, box-shadow .25s;
  }
  .btn-backtop.visible { opacity: 1; pointer-events: auto; }
  .btn-backtop svg { fill: #fff; width: 24px; height: 24px; }

  /* 响应式 */
  @media (max-width: 768px) {
    .side-toolbar { right: 10px; bottom: 60px; }
    .side-toolbar a { width: 46px; height: 46px; }
  }