/* 个人学习网站 - 明亮风格 */
:root {
  --bg: #faf9f7;
  --bg-subtle: #f3f1ed;
  --surface: #ffffff;
  --border: #e8e6e1;
  --text: #2d2a26;
  --text-muted: #6b6560;
  --accent: #0d9488;
  --accent-hover: #0f766e;
  --accent-soft: rgba(13, 148, 136, 0.12);
  --shadow: 0 1px 3px rgba(45, 42, 38, 0.06);
  --shadow-hover: 0 8px 24px rgba(45, 42, 38, 0.08);
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* 背景微纹理 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image: radial-gradient(circle at 20% 20%, rgba(13, 148, 136, 0.04) 0%, transparent 50%),
                    radial-gradient(circle at 80% 80%, rgba(13, 148, 136, 0.03) 0%, transparent 45%);
  pointer-events: none;
  z-index: 0;
}

/* 导航 */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2.25rem;
  z-index: 100;
  box-shadow: var(--shadow);
}

.nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}

.nav a:hover {
  color: var(--accent);
}

.nav a.active {
  color: var(--accent);
  position: relative;
}

.nav a.active::after {
  content: "";
  position: absolute;
  bottom: -18px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent);
}

/* 主内容区 */
.main {
  position: relative;
  z-index: 1;
  max-width: 680px;
  margin: 0 auto;
  padding: 100px 28px 80px;
}

h1 {
  font-size: 1.9rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
  color: var(--text);
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 2.75rem;
  line-height: 1.6;
}

.section {
  margin-bottom: 2.75rem;
}

.section h2 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
}

.section p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 0.5rem;
}

/* 卡片 */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.4rem 1.6rem;
  margin-bottom: 1rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.25s ease, border-color 0.25s ease, transform 0.2s ease;
  border-left: 4px solid transparent;
}

.card:hover {
  box-shadow: var(--shadow-hover);
  border-left-color: var(--accent);
}

.card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text);
}

.card p {
  margin-bottom: 0;
  font-size: 0.92rem;
  color: var(--text-muted);
}

.card-link {
  color: var(--accent);
  text-decoration: none;
  display: inline-block;
  margin-top: 0.6rem;
  font-weight: 500;
  font-size: 0.9rem;
  transition: color 0.2s;
}

.card-link:hover {
  color: var(--accent-hover);
}

/* 页脚 */
.footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 2.25rem 28px;
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
  background: var(--surface);
}

.footer a {
  color: var(--accent);
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}

/* 学习列表 */
.topic-list {
  list-style: none;
}

.topic-list li {
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.topic-list li:last-child {
  border-bottom: none;
}

.topic-list a {
  color: var(--text);
  text-decoration: none;
  flex: 1;
}

.topic-list a:hover {
  color: var(--accent);
}

.tag {
  font-size: 0.75rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.25rem 0.6rem;
  border-radius: 8px;
  flex-shrink: 0;
  font-weight: 500;
}

/* 关于页 */
.profile {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.profile p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.profile .highlight {
  color: var(--accent);
  font-weight: 600;
}

/* 首页图片展示 */
.hero-pics {
  margin-bottom: 2.75rem;
}

.hero-pics-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  margin-top: 0.5rem;
}

@media (min-width: 640px) {
  .hero-pics-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.hero-pic {
  margin: 0;
  background: var(--surface);
  border-radius: 14px;
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: box-shadow 0.25s ease;
}

.hero-pic:hover {
  box-shadow: var(--shadow-hover);
}

.hero-pic img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  display: block;
}

.hero-pic figcaption {
  padding: 1rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.hero-pic strong {
  font-size: 0.95rem;
  color: var(--text);
  font-weight: 600;
}

.hero-pic span {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.55;
}