/* ========== CSS 变量 ========== */
:root {
  --bg-color: #ffffff;
  --text-color: #333333;
  --text-secondary: #666666;
  --border-color: #e5e5e5;
  --link-color: #0066cc;
  --link-hover: #0052a3;
  --tag-bg: #f0f0f0;
  --tag-color: #555555;
  --header-bg: #ffffff;
  --code-bg: #f5f5f5;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --text-secondary: #a0a0a0;
    --border-color: #333333;
    --link-color: #4da6ff;
    --link-hover: #80c5ff;
    --tag-bg: #2a2a2a;
    --tag-color: #b0b0b0;
    --header-bg: #1a1a1a;
    --code-bg: #2a2a2a;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  }
}

/* ========== 基础样式 ========== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-color);
  background-color: var(--bg-color);
  transition: background-color 0.3s, color 0.3s;
}

a {
  color: var(--link-color);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--link-hover);
}

/* ========== 布局 ========== */
.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.main {
  flex: 1;
  padding: 40px 0;
}

/* ========== 头部导航 ========== */
.site-header {
  padding: 20px 0;
  border-bottom: 1px solid var(--border-color);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-color);
}

.nav-links {
  display: flex;
  gap: 24px;
}

.nav-link {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

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

/* ========== 主页 ========== */
.home {
  text-align: center;
}

.home-title {
  font-size: 2.5rem;
  margin-bottom: 12px;
  font-weight: 700;
}

.home-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 48px;
}

.home-actions {
  margin-top: 48px;
  display: flex;
  gap: 16px;
  justify-content: center;
}

.btn {
  display: inline-block;
  padding: 10px 24px;
  background: var(--link-color);
  color: white;
  border-radius: 6px;
  font-size: 0.95rem;
  transition: background 0.2s;
}

.btn:hover {
  background: var(--link-hover);
  color: white;
}

/* ========== 文章列表 ========== */
.posts {
  text-align: left;
}

.post-item {
  padding: 24px 0;
  border-bottom: 1px solid var(--border-color);
}

.post-item:last-child {
  border-bottom: none;
}

.post-title {
  font-size: 1.4rem;
  margin-bottom: 8px;
  font-weight: 600;
}

.post-title a {
  color: var(--text-color);
}

.post-title a:hover {
  color: var(--link-color);
}

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

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

.tag {
  display: inline-block;
  padding: 2px 8px;
  background: var(--tag-bg);
  color: var(--tag-color);
  border-radius: 4px;
  font-size: 0.8rem;
}

.post-summary {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* ========== 单篇文章 ========== */
.post {
  max-width: 100%;
}

.post-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-color);
}

.post-header .post-title {
  font-size: 2rem;
  margin-bottom: 16px;
}

.post-content {
  font-size: 1.05rem;
  line-height: 1.8;
}

.post-content h1,
.post-content h2,
.post-content h3,
.post-content h4,
.post-content h5,
.post-content h6 {
  margin: 32px 0 16px;
  font-weight: 600;
  line-height: 1.3;
}

.post-content h2 {
  font-size: 1.6rem;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.post-content h3 {
  font-size: 1.3rem;
}

.post-content p {
  margin-bottom: 16px;
}

.post-content ul,
.post-content ol {
  margin-bottom: 16px;
  padding-left: 24px;
}

.post-content li {
  margin-bottom: 8px;
}

.post-content code {
  background: var(--code-bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: "SF Mono", Monaco, "Cascadia Code", monospace;
  font-size: 0.9em;
}

.post-content pre {
  background: var(--code-bg);
  padding: 16px;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 16px;
}

.post-content pre code {
  background: none;
  padding: 0;
}

.post-content blockquote {
  border-left: 4px solid var(--link-color);
  padding-left: 16px;
  margin: 16px 0;
  color: var(--text-secondary);
}

.post-content hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 32px 0;
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 16px;
}

.post-content th,
.post-content td {
  padding: 8px 12px;
  border: 1px solid var(--border-color);
  text-align: left;
}

.post-content th {
  background: var(--tag-bg);
  font-weight: 600;
}

.post-nav {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
}

.post-nav .prev {
  text-align: left;
}

.post-nav .next {
  text-align: right;
}

/* ========== 标签页 ========== */
.terms {
  text-align: center;
}

.terms h1 {
  font-size: 1.8rem;
  margin-bottom: 32px;
}

.terms-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

.term-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--tag-bg);
  border-radius: 20px;
  color: var(--text-color);
  transition: background 0.2s;
}

.term-item:hover {
  background: var(--border-color);
  color: var(--text-color);
}

.term-count {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* ========== 图片优化 ========== */
.post-content figure {
  margin: 24px 0;
  text-align: center;
}

.post-content img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: var(--shadow);
  transition: transform 0.2s, box-shadow 0.2s;
}

.post-content img:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.post-content figcaption {
  margin-top: 12px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-style: italic;
}

/* 图片加载占位 */
.post-content img[loading="lazy"] {
  background: linear-gradient(90deg, var(--tag-bg) 25%, transparent 25%, transparent 50%, var(--tag-bg) 50%, var(--tag-bg) 75%, transparent 75%, transparent);
  background-size: 20px 20px;
}

/* ========== 页脚 ========== */
.site-footer {
  padding: 24px 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
}

/* ========== 响应式 ========== */
@media (max-width: 600px) {
  .home-title {
    font-size: 1.8rem;
  }

  .post-header .post-title {
    font-size: 1.5rem;
  }

  .nav {
    flex-direction: column;
    gap: 16px;
  }

  .nav-links {
    gap: 16px;
  }

  .home-actions {
    flex-direction: column;
    align-items: center;
  }

  .post-nav {
    flex-direction: column;
    gap: 16px;
  }

  .post-nav .prev,
  .post-nav .next {
    text-align: center;
  }
}