* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  font-family: Arial, Helvetica, "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", sans-serif;
}

body {
  color: white;
}

/* 顶部导航栏 */
.site-header {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 10;

  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 40px 70px;
}

/* 左上角 Lab 名称 */
.lab-name a {
  color: white;
  text-decoration: none;
  font-size: 46px;
  font-weight: 800;
  letter-spacing: 2px;
  text-shadow: 2px 2px 6px rgba(0, 0, 0, 0.6);
}

/* 右上角菜单 */
.main-nav {
  display: flex;
  gap: 32px;
  align-items: center;
}

.main-nav a {
  color: white;
  text-decoration: none;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.5px;
  text-shadow: 1px 1px 5px rgba(0, 0, 0, 0.7);
}

.main-nav a:hover {
  text-decoration: underline;
}

/* 首页大图区域 */
.hero {
  position: relative;
  min-height: 86vh;

  background-image: url("../images/hero.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;

  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}

/* 图片上的深色遮罩，让白字更清楚 */
.hero-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 35, 70, 0.35);
}

/* 中间大标题 */
.hero-content {
  position: relative;
  z-index: 2;
  max-width: 1200px;
  padding: 20px;
}

.hero-content h1 {
  margin: 0 0 25px 0;
  font-size: 96px;
  line-height: 1.05;
  font-weight: 900;
  letter-spacing: 4px;
  text-transform: uppercase;
  text-shadow: 4px 4px 10px rgba(0, 0, 0, 0.65);
}

.hero-content h2 {
  margin: 0 auto;
  max-width: 1400px;
  font-size: 32px;
  line-height: 1.35;
  font-weight: 500;
  text-shadow: 3px 3px 8px rgba(0, 0, 0, 0.65);
}

/* 底部蓝色机构条 */
.institute-bar {
  background: #0756a6;
  padding: 28px 20px;
  text-align: center;
}

.institute-bar p {
  margin: 0;
  font-size: 28px;
  letter-spacing: 1px;
  font-weight: 400;
}

/* 页脚 */
.footer {
  background: #06498d;
  color: white;
  text-align: center;
  padding: 15px;
  font-size: 14px;
}

/* 平板适配 */
@media screen and (max-width: 1000px) {
  .site-header {
    padding: 30px 35px;
    flex-direction: column;
    gap: 20px;
  }

  .lab-name a {
    font-size: 38px;
  }

  .main-nav {
    flex-wrap: wrap;
    justify-content: center;
    gap: 18px;
  }

  .hero-content h1 {
    font-size: 70px;
  }

  .hero-content h2 {
    font-size: 26px;
  }

  .institute-bar p {
    font-size: 22px;
  }
}

/* 手机适配 */
@media screen and (max-width: 600px) {
  .site-header {
    padding: 24px 20px;
  }

  .lab-name a {
    font-size: 30px;
  }

  .main-nav a {
    font-size: 14px;
  }

  .hero {
    min-height: 82vh;
  }

  .hero-content h1 {
    font-size: 46px;
  }

  .hero-content h2 {
    font-size: 20px;
  }

  .institute-bar p {
    font-size: 17px;
  }
}