#fps-panel {
      position: fixed;
      top: 0;
      right: 0;
      z-index: 99999;
      background: rgba(0, 0, 0, 0.7);
      color: white;
      font-size: 14px;
      padding: 4px 12px;
      border-radius: 0 0 0 8px;
      pointer-events: none; /* 不阻挡点击 */
      backdrop-filter: blur(4px);
      transition: color 0.3s, background 0.3s;
    }
    /* 移动端适配：左下角 */
    @media (max-width: 768px) {
      #fps-panel {
        top: auto;
        bottom: 0;
        left: 0;
        right: auto;
        border-radius: 0 8px 0 0; /* 右上圆角，左下平直 */
      }
    }

    /* 隐藏面板（开关控制） */
    #fps-panel.hidden {
      opacity: 0;
      visibility: hidden;
      transition: opacity 0.3s, visibility 0.3s;
    }