:root {
  --bg-primary: #0a0a0c;
  --bg-secondary: #141418;
  --bg-card: #1c1c22;
  --bg-card-hover: #24242c;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-focus: rgba(255, 255, 255, 0.2);
  --text-primary: #f0f0f3;
  --text-secondary: #9e9ea8;
  --text-muted: #666672;
  --accent: #e2e2e8;
  --accent-blue: #3b82f6;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --max-width: 1040px;
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.15s ease;
}

a:hover {
  color: #ffffff;
}

/* 顶部导航 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 12, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}

.brand-icon {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

.brand-badge {
  font-size: 0.72rem;
  font-weight: 400;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 2px 8px;
  border-radius: 999px;
  margin-left: 4px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-link {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

/* 主内容区 */
main {
  flex: 1;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

/* Hero Section */
.hero {
  padding: 4.5rem 0 3.5rem;
  border-bottom: 1px solid var(--border-color);
}

.eyebrow {
  display: inline-block;
  font-size: 0.8rem;
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.hero h1 {
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.25;
  margin-bottom: 1.25rem;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 640px;
  line-height: 1.7;
}

/* 笔记列表网格 */
.section-title {
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin: 2.5rem 0 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border-color);
}

.notes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.note-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.note-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-focus);
  background: var(--bg-card);
}

.note-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.note-tag {
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.05);
  padding: 2px 6px;
  border-radius: 4px;
}

.note-card h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 0.6rem;
  line-height: 1.4;
}

.note-card p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
}

.note-image {
  margin-top: 1.25rem;
  border-radius: 8px;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--border-color);
}

.note-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.3s ease;
}

.note-card:hover .note-image img {
  transform: scale(1.02);
}

/* 核心原则与方法 */
.principles {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.principle-box {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.5rem;
}

.principle-box h4 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.principle-box p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* 文章详情页样式 */
.article-header {
  margin-bottom: 2.5rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 2rem;
}

.article-header h1 {
  font-size: clamp(1.8rem, 3.5vw, 2.3rem);
  font-weight: 700;
  margin: 0.8rem 0;
  line-height: 1.3;
}

.article-body {
  font-size: 1.05rem;
  line-height: 1.85;
  color: #d1d1dc;
  max-width: 780px;
}

.article-body h2 {
  font-size: 1.45rem;
  font-weight: 600;
  margin: 2.5rem 0 1rem;
  color: var(--text-primary);
}

.article-body h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 2rem 0 0.8rem;
  color: var(--text-primary);
}

.article-body p {
  margin-bottom: 1.25rem;
}

.article-body ul, .article-body ol {
  margin: 1rem 0 1.5rem 1.5rem;
}

.article-body li {
  margin-bottom: 0.5rem;
}

.article-body blockquote {
  border-left: 3px solid var(--text-muted);
  padding: 0.5rem 0 0.5rem 1.25rem;
  margin: 1.5rem 0;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border-radius: 0 6px 6px 0;
}

.code-block {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.2rem;
  margin: 1.5rem 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: #e0e0e8;
}

/* 页脚合规要求（工信部备案规范） */
.site-footer {
  border-top: 1px solid var(--border-color);
  background: var(--bg-secondary);
  padding: 2.5rem 1.5rem 2rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-content {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-compliance {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.6;
  text-align: center;
}

.miit-link {
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.miit-link:hover {
  color: #ffffff;
  text-decoration: underline;
}

@media (max-width: 640px) {
  .nav-links {
    gap: 1rem;
  }
  .hero {
    padding: 3rem 0 2rem;
  }
}