/* 默认隐藏，避免加载时闪烁 */
.pc-only,
.mob-only {
  display: none;
}

/* PC 端（屏幕宽度 ≥ 768px）显示 .pc-only */
@media (min-width: 768px) {
  .pc-only {
    display: block;
  }
}

/* 手机端（屏幕宽度 < 768px）显示 .mobile-only */
@media (max-width: 767px) {
  .mob-only {
    display: block;
  }

  .background video {
    display: none !important;
  }

  .background img {
    display: block !important;
  }
}

#nav-pc nav {
  position: absolute;
  top: 20px;
  right: 30px;
  z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  border-radius: 30px;
  padding: 10px 10px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease-in-out;
}

#nav-pc img {
max-height: 50px;
    position: fixed;
    left: 0;
    top: 15px;

}

#nav-pc .menu {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 20px;
}

#nav-pc .menu li a {
  text-decoration: none;
  color: #333;
  padding: 3px 10px;
  border-radius: 20px;
  transition: all 0.3s ease;
  font-weight: 500;
}

#nav-pc .menu li.active a {
  background: #3498db;
  color: white;
}

#nav-pc .menu li a:hover {
  background: #f0f0f0;
}

#nav-mob nav {
  position: fixed;
  left: 0;
  right: 0;
  margin: 0 auto;
  z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  padding: 10px 20px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease-in-out;
}

#nav-mob img {
  max-height: 20px;
  position: absolute;

}

#nav-mob .menu {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: flex-end;
}

#nav-mob .menu li a {
  text-decoration: none;
  color: #333;
  padding: 5px 10px;
  border-radius: 20px;
  transition: all 0.3s ease;
  font-weight: 500;
}

#nav-mob .menu li.active a {
  background: #3498db;
  color: white;
}

#nav-pc .menu li a:hover {
  background: #f0f0f0;
}

/* 视频容器样式 */
.background {
  position: absolute;
  width: 100%;
  height: 100%;
  overflow: hidden;
  top: 0;
  left: 0;
  z-index: -1;
}

.background video {
  min-width: 100%;
  min-height: 100%;
  width: auto;
  height: auto;
  object-fit: cover;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

/* 图片样式 */
.background img {
  object-fit: cover;
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  display: none;
}

/* container-1 */
.content {
  position: absolute;
  z-index: 0;
  width: 100%;
  left: 0;
  transform: translate3d(0, 0, 0);
  /* 防止浏览器渲染闪烁 */
}

#container-1 .content .headline-pc {
  left: 0;
  position: absolute;
  text-align: center;
  color: #ffffff;
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
  font-size: 3.5rem;
  right: 0;
  margin: -50px auto;
}

#container-1 .content .headline-pc .subscript {
  position: relative;
  vertical-align: sub;
  font-size: 0.35em;
  opacity: 0.9;
}

#container-1 .content .headline-mob {
  text-align: center;
  /* 水平居中 */
  display: flex;
  /* 启用Flexbox */
  flex-direction: column;
  /* 垂直方向排列 */
  align-items: center;
  /* 交叉轴居中 */
  justify-content: center;
  /* 主轴居中 */
  color: #ffffff;
  /* 白色文字，适合深色背景 */
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
  /* 文字阴影，增强可读性 */
  font-size: 1.5rem;
}

#container-1 .content .headline-mob .subscript {
  position: relative;
  vertical-align: sub;
  font-size: 0.65em;
  /* 相对于h1-mob的字体大小进行缩放 */
  opacity: 0.9;
  /* 可选：让下标稍淡一点 */
  left: 10%;
}