/* ===========================
   前台样式 - 学术风格
   =========================== */

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  background: #f5f7fa;
  color: #333;
  line-height: 1.7;
}

/* 导航栏 */
nav {
  position: sticky;
  top: 0;
  background: #1a3a5c;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

nav ul {
  list-style: none;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0;
}

nav ul li a {
  display: block;
  color: #d4e6f8;
  text-decoration: none;
  padding: 16px 24px;
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 0.5px;
  transition: background 0.2s, color 0.2s;
}

nav ul li a:hover {
  background: #2a5a8c;
  color: #fff;
}

/* 顶部 Hero */
.hero {
  background: linear-gradient(135deg, #1a3a5c 0%, #2a6496 100%);
  color: #fff;
  padding: 60px 20px 50px;
}

.hero-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 40px;
}

.hero-photo {
  flex-shrink: 0;
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: rgba(255,255,255,0.15);
  border: 4px solid rgba(255,255,255,0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 60px;
  overflow: hidden;
}

.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-info h1 {
  font-size: 42px;
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: 2px;
}

.hero-info .title-badge {
  display: inline-block;
  background: rgba(255,255,255,0.2);
  border: 1px solid rgba(255,255,255,0.4);
  color: #e8f4fd;
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 14px;
  margin-bottom: 16px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  margin-top: 8px;
}

.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
  color: #c8e0f4;
  font-size: 14px;
}

.hero-meta-item .icon {
  font-size: 16px;
}

/* 主内容区 */
.main-content {
  max-width: 1100px;
  margin: 0 auto;
  padding: 30px 20px 60px;
}

/* Section 卡片 */
.section-card {
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.07);
  margin-bottom: 30px;
  overflow: hidden;
}

.section-header {
  background: linear-gradient(90deg, #1a3a5c, #2a6496);
  color: #fff;
  padding: 16px 28px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.section-header .sec-icon {
  font-size: 20px;
}

.section-header h2 {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 1px;
}

.section-body {
  padding: 28px 32px;
}

/* 个人简介 Markdown 渲染 */
.bio-content,
.research-content {
  font-size: 15px;
  line-height: 1.85;
  color: #444;
}

.bio-content p,
.research-content p {
  margin-bottom: 12px;
}

.bio-content strong,
.research-content strong {
  color: #1a3a5c;
  font-weight: 600;
}

.bio-content ul,
.research-content ul {
  padding-left: 20px;
  margin-bottom: 14px;
}

.bio-content ul li,
.research-content ul li {
  margin-bottom: 6px;
  color: #555;
}

/* 课程列表 */
.courses-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.course-tag {
  background: linear-gradient(135deg, #e8f4fd, #d0e8f8);
  color: #1a3a5c;
  border: 1px solid #b8d8f0;
  padding: 8px 20px;
  border-radius: 25px;
  font-size: 14px;
  font-weight: 500;
  transition: transform 0.15s, box-shadow 0.15s;
}

.course-tag:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(26,58,92,0.15);
}

/* 页脚 */
footer {
  background: #1a3a5c;
  color: #7a9fc0;
  text-align: center;
  padding: 22px;
  font-size: 13px;
}

/* 响应式 */
@media (max-width: 700px) {
  .hero-inner {
    flex-direction: column;
    text-align: center;
  }

  .hero-meta {
    justify-content: center;
  }

  .hero-info h1 {
    font-size: 30px;
  }

  nav ul li a {
    padding: 12px 14px;
    font-size: 13px;
  }

  .section-body {
    padding: 20px 18px;
  }
}