/* ===== CSS 变量 ===== */
:root {
  --bg: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-card: #ffffff;
  --text: #1a1a1a;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --border: #e5e7eb;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-hover: 0 4px 12px rgba(0,0,0,0.12);
  --max-width: 720px;
  --max-width-wide: 960px;
  --radius: 12px;
  --transition: 0.25s ease;
}

[data-theme="dark"] {
  --bg: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #161b22;
  --text: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent: #58a6ff;
  --accent-light: #1a2332;
  --border: #30363d;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-hover: 0 4px 12px rgba(0,0,0,0.4);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  font-size: 16px;
  transition: background var(--transition), color var(--transition);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { text-decoration: underline; }

/* ===== 阅读进度条 ===== */
#progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0%;
  background: var(--accent);
  z-index: 1000;
  transition: width 0.1s ease;
}

/* ===== 导航栏 ===== */
#navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
  transition: background var(--transition);
}

[data-theme="dark"] #navbar {
  background: rgba(13,17,23,0.85);
}

.nav-container {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.nav-logo:hover { text-decoration: none; color: var(--accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 8px;
  transition: all var(--transition);
}

.nav-link:hover { color: var(--text); background: var(--bg-secondary); text-decoration: none; }
.nav-link.active { color: var(--accent); }

.theme-toggle {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 8px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

.theme-toggle:hover { background: var(--bg-secondary); color: var(--text); }

.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: block; }

/* ===== 主内容 ===== */
#app {
  flex: 1;
  width: 100%;
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: 48px 24px;
}

/* ===== 首页 Hero ===== */
.hero {
  text-align: center;
  padding: 60px 0 48px;
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 16px;
  line-height: 1.2;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 480px;
  margin: 0 auto;
}

/* ===== 搜索框 ===== */
.search-box {
  max-width: 400px;
  margin: 0 auto 48px;
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 12px 20px 12px 44px;
  border: 1px solid var(--border);
  border-radius: 24px;
  font-size: 0.95rem;
  background: var(--bg-card);
  color: var(--text);
  transition: all var(--transition);
  outline: none;
}

.search-box input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.search-box svg {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

/* ===== 标签筛选 ===== */
.tag-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  margin-bottom: 40px;
}

.tag-filter button {
  padding: 6px 16px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--bg-card);
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all var(--transition);
}

.tag-filter button:hover { border-color: var(--accent); color: var(--accent); }
.tag-filter button.active { background: var(--accent); color: #fff; border-color: var(--accent); }

/* ===== 文章列表 ===== */
.post-list { display: flex; flex-direction: column; gap: 16px; }

.post-card {
  display: block;
  padding: 28px 32px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: all var(--transition);
  cursor: pointer;
  text-decoration: none;
}

.post-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.post-card-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.post-card-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
  line-height: 1.4;
}

.post-card-excerpt {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 14px;
}

.post-card-tags { display: flex; gap: 8px; flex-wrap: wrap; }

.post-card-tags span {
  font-size: 0.8rem;
  padding: 3px 10px;
  border-radius: 6px;
  background: var(--accent-light);
  color: var(--accent);
}

/* ===== 文章详情 ===== */
.post-detail { max-width: var(--max-width); margin: 0 auto; }

.post-detail-header { margin-bottom: 40px; }

.post-detail-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin-bottom: 16px;
}

.post-detail-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.post-detail-tags { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 16px; }
.post-detail-tags span {
  font-size: 0.8rem;
  padding: 3px 12px;
  border-radius: 6px;
  background: var(--accent-light);
  color: var(--accent);
}

.post-detail-body {
  font-size: 1.05rem;
  line-height: 1.9;
  color: var(--text);
}

.post-detail-body h1, .post-detail-body h2, .post-detail-body h3 {
  font-weight: 700;
  margin-top: 2em;
  margin-bottom: 0.6em;
  letter-spacing: -0.01em;
}

.post-detail-body h1 { font-size: 1.8rem; }
.post-detail-body h2 { font-size: 1.5rem; }
.post-detail-body h3 { font-size: 1.25rem; }

.post-detail-body p { margin-bottom: 1.2em; }

.post-detail-body code {
  font-family: 'SF Mono', 'Fira Code', Consolas, monospace;
  font-size: 0.9em;
  padding: 2px 6px;
  background: var(--bg-secondary);
  border-radius: 4px;
  color: var(--accent);
}

.post-detail-body pre {
  padding: 20px 24px;
  background: var(--bg-secondary);
  border-radius: 10px;
  overflow-x: auto;
  margin: 1.5em 0;
  border: 1px solid var(--border);
}

.post-detail-body pre code {
  padding: 0;
  background: none;
  color: var(--text);
  font-size: 0.9rem;
  line-height: 1.6;
}

.post-detail-body blockquote {
  border-left: 4px solid var(--accent);
  padding: 8px 20px;
  margin: 1.5em 0;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border-radius: 0 8px 8px 0;
}

.post-detail-body ul, .post-detail-body ol { margin: 1em 0 1.2em 1.5em; }
.post-detail-body li { margin-bottom: 0.5em; }

.post-detail-body img { max-width: 100%; border-radius: 8px; margin: 1.5em 0; }

.post-detail-body a { border-bottom: 1px solid var(--accent); }

.post-detail-body hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }

.post-detail-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5em 0;
}

.post-detail-body th, .post-detail-body td {
  border: 1px solid var(--border);
  padding: 8px 14px;
  text-align: left;
}

.post-detail-body th { background: var(--bg-secondary); font-weight: 600; }

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 32px;
  transition: color var(--transition);
}

.back-link:hover { color: var(--accent); text-decoration: none; }

/* ===== 关于页面 ===== */
.about-page { max-width: var(--max-width); margin: 0 auto; }

.about-page h1 { font-size: 2rem; font-weight: 800; margin-bottom: 24px; letter-spacing: -0.02em; }

.about-content { font-size: 1.05rem; line-height: 1.9; }

.about-content p { margin-bottom: 1.2em; color: var(--text-secondary); }

.social-links {
  display: flex;
  gap: 16px;
  margin-top: 32px;
  flex-wrap: wrap;
}

.social-links a {
  padding: 10px 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: all var(--transition);
}

.social-links a:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }

/* ===== 空状态 ===== */
.empty-state {
  text-align: center;
  padding: 80px 20px;
  color: var(--text-muted);
}

.empty-state h3 { font-size: 1.2rem; margin-bottom: 8px; color: var(--text-secondary); }

/* ===== 页脚 ===== */
footer {
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  margin-top: auto;
}

.footer-container {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-container p { font-size: 0.85rem; color: var(--text-muted); }

.footer-links { display: flex; gap: 16px; }
.footer-links a { font-size: 0.85rem; color: var(--text-muted); }
.footer-links a:hover { color: var(--accent); }

/* ===== 返回顶部 ===== */
#back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition);
  box-shadow: var(--shadow);
  z-index: 90;
}

#back-to-top.show { opacity: 1; visibility: visible; }
#back-to-top:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-2px); }

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.8rem; }
  .hero p { font-size: 1rem; }
  .post-card { padding: 20px 22px; }
  .post-card-title { font-size: 1.15rem; }
  .post-detail-title { font-size: 1.6rem; }
  .nav-container { padding: 0 16px; }
  #app { padding: 32px 16px; }
  .footer-container { flex-direction: column; text-align: center; }
  #back-to-top { bottom: 20px; right: 20px; }
}

/* ===== 加载动画 ===== */
.fade-in { animation: fadeIn 0.4s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}