* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  html, body {
    width: 100%;
    height: 100%;
    overflow: hidden;
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  }
  
  /* 视频容器 */
  .video-container {
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    background-color: #ffffff; /* 手机端背景为纯白色 */
  }
  
  /* 默认（电脑端）：全屏铺满，不留黑边 */
  #bg-video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
  }
  
  /* 移动端响应式：完整展示视频，留白区域显示纯白背景 */
  @media (max-width: 768px) {
    #bg-video {
      object-fit: contain; /* 手机端完整显示画面，不裁剪 */
    }
  }
  
  /* 极简大气开场遮罩 */
  .overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(0, 0, 0, 1);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    z-index: 999;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 24px;
    transition: opacity 0.5s ease, visibility 0.5s;
  }
  
  .content-box {
    max-width: 480px;
    width: 100%;
    text-align: center;
  }
  
  /* 声明文字 */
  .statement {
    font-size: 18px;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.85);
    letter-spacing: 1px;
    font-weight: 300;
    margin-bottom: 36px;
  }
  
  /* 极简按钮 */
  .start-btn {
    background: transparent;
    color: #ffffff;
    border: 1px solid rgba(255, 255, 255, 0.5);
    padding: 12px 36px;
    font-size: 14px;
    letter-spacing: 2px;
    border-radius: 40px;
    cursor: pointer;
    transition: all 0.3s ease;
  }
  
  .start-btn:hover {
    background: #ffffff;
    color: #000000;
    border-color: #ffffff;
  }
  
  .overlay.hidden {
    opacity: 0;
    visibility: hidden;
  }