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

:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #dbeafe;
  --text: #1e293b;
  --text-secondary: #64748b;
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --border: #e2e8f0;
  --nav-bg: #0f172a;
  --nav-text: #f1f5f9;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.06);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

a:hover {
  color: var(--primary-dark);
}

img {
  max-width: 100%;
  height: auto;
}

/* ── Container ── */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ── Navigation ── */
.navbar {
  background: var(--nav-bg);
  color: var(--nav-text);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.navbar .logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.5px;
}

.navbar .logo:hover {
  color: #93c5fd;
}

.navbar .logo span {
  color: var(--primary);
}

.nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
}

.nav-links a {
  color: var(--nav-text);
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
  padding-bottom: 2px;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: width 0.25s;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-links a:hover {
  color: #fff;
}

.nav-links a.active {
  color: #93c5fd;
}

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--nav-text);
  border-radius: 2px;
  transition: all 0.3s;
}

/* ── Hero ── */
.hero {
  background: linear-gradient(135deg, var(--nav-bg) 0%, #1e3a5f 100%);
  color: #fff;
  padding: 80px 0 60px;
  text-align: center;
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 12px;
  line-height: 1.2;
}

.hero h1 span {
  color: #60a5fa;
}

.hero p {
  font-size: 1.1rem;
  color: #cbd5e1;
  max-width: 600px;
  margin: 0 auto 28px;
}

.hero .btn {
  display: inline-block;
  padding: 12px 32px;
  background: var(--primary);
  color: #fff;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.2s, transform 0.15s;
}

.hero .btn:hover {
  background: var(--primary-dark);
  color: #fff;
  transform: translateY(-1px);
}

/* ── Section ── */
.section {
  padding: 60px 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 32px;
  padding-bottom: 12px;
  border-bottom: 3px solid var(--primary-light);
}

/* ── Article Grid ── */
.article-grid {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
}

.posts-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.post-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  transition: box-shadow 0.25s, transform 0.2s;
}

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

.post-card .meta {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 8px;
  display: flex;
  gap: 12px;
  align-items: center;
}

.post-card .meta .tag {
  display: inline-block;
  padding: 2px 10px;
  background: var(--primary-light);
  color: var(--primary-dark);
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 500;
}

.post-card h2 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.post-card h2 a {
  color: var(--text);
}

.post-card h2 a:hover {
  color: var(--primary);
}

.post-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.post-card .read-more {
  display: inline-block;
  margin-top: 12px;
  font-size: 0.9rem;
  font-weight: 600;
}

/* ── Sidebar ── */
.sidebar {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.sidebar-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.sidebar-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--primary-light);
}

.sidebar-card ul {
  list-style: none;
}

.sidebar-card li {
  margin-bottom: 8px;
}

.sidebar-card li a {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.sidebar-card li a:hover {
  color: var(--primary);
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag-cloud a {
  display: inline-block;
  padding: 4px 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 16px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: all 0.2s;
}

.tag-cloud a:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* ── Article Page ── */
.article-full {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.article-full header {
  margin-bottom: 32px;
}

.article-full h1 {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 12px;
}

.article-full .meta {
  font-size: 0.9rem;
  color: var(--text-secondary);
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.article-full .meta .tag {
  display: inline-block;
  padding: 2px 12px;
  background: var(--primary-light);
  color: var(--primary-dark);
  border-radius: 12px;
  font-size: 0.85rem;
}

.article-body {
  font-size: 1.05rem;
  line-height: 1.85;
  color: var(--text);
}

.article-body h2 {
  font-size: 1.4rem;
  margin: 32px 0 12px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--border);
}

.article-body h3 {
  font-size: 1.15rem;
  margin: 24px 0 10px;
}

.article-body p {
  margin-bottom: 16px;
}

.article-body ul,
.article-body ol {
  margin: 0 0 16px 20px;
}

.article-body li {
  margin-bottom: 6px;
}

.article-body code {
  font-family: "JetBrains Mono", "Fira Code", "Cascadia Code", Consolas, monospace;
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
}

.article-body pre {
  background: #1e293b;
  color: #e2e8f0;
  padding: 20px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 20px 0;
  font-size: 0.9rem;
  line-height: 1.6;
}

.article-body pre code {
  background: transparent;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

.article-body blockquote {
  border-left: 4px solid var(--primary);
  padding: 12px 20px;
  margin: 20px 0;
  background: var(--primary-light);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: #334155;
}

/* ── About Page ── */
.about-page {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.about-page h1 {
  font-size: 2rem;
  margin-bottom: 24px;
}

.about-page .avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: var(--primary);
  margin-bottom: 20px;
}

.about-page .bio {
  font-size: 1.05rem;
  line-height: 1.8;
  margin-bottom: 24px;
}

.about-page .info-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 24px;
}

.about-page .info-item {
  padding: 12px 16px;
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.about-page .info-item strong {
  display: block;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

/* ── Footer ── */
.footer {
  background: var(--nav-bg);
  color: #94a3b8;
  text-align: center;
  padding: 24px 0;
  font-size: 0.9rem;
  margin-top: auto;
}

.footer a {
  color: #93c5fd;
}

.footer a:hover {
  color: #fff;
}

/* ── Back to Top ── */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 44px;
  height: 44px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.2rem;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .article-grid {
    grid-template-columns: 1fr;
  }

  .hero h1 {
    font-size: 1.8rem;
  }

  .hero p {
    font-size: 1rem;
  }

  .hero {
    padding: 50px 0 40px;
  }

  .section {
    padding: 40px 0;
  }

  .article-full,
  .about-page {
    padding: 24px;
  }

  .article-full h1 {
    font-size: 1.5rem;
  }

  .about-page .info-grid {
    grid-template-columns: 1fr;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    flex-direction: column;
    padding: 16px 20px;
    gap: 12px;
    border-top: 1px solid #1e3a5f;
  }

  .nav-links.open {
    display: flex;
  }

  .hamburger {
    display: flex;
  }
}