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

:root {
  --primary: #2563eb;
  --primary-light: #3b82f6;
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.1);
  --radius: 8px;
  --max-width: 1200px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a;
    --bg-card: #1e293b;
    --text: #f1f5f9;
    --text-secondary: #94a3b8;
    --border: #334155;
  }
}

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: 1.6;
}

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

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

/* Header */
.header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  gap: 20px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 20px;
  font-weight: 700;
  color: var(--text);
  white-space: nowrap;
}

.logo-icon {
  font-size: 24px;
}

.search-box {
  flex: 1;
  max-width: 400px;
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 8px 16px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  outline: none;
  transition: border-color 0.2s;
}

.search-box input:focus {
  border-color: var(--primary);
}

/* Nav */
.nav {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  gap: 4px;
  overflow-x: auto;
}

.nav-item {
  padding: 12px 16px;
  font-size: 14px;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.2s;
  white-space: nowrap;
}

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

.nav-item.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 500;
}

/* Main */
.main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 20px;
}

/* News List */
.news-list {
  display: grid;
  gap: 16px;
}

.news-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 20px;
  cursor: pointer;
  transition: all 0.2s;
}

.news-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-1px);
}

.news-card-header {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 8px;
}

.news-category {
  font-size: 20px;
  flex-shrink: 0;
}

.news-card-title {
  font-size: 16px;
  font-weight: 600;
  line-height: 1.4;
  flex: 1;
}

.news-card-summary {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.news-card-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 12px;
  color: var(--text-secondary);
}

.news-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.tag {
  padding: 2px 8px;
  background: var(--bg);
  border-radius: 4px;
  font-size: 12px;
  color: var(--text-secondary);
}

/* Detail Page */
.detail-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
}

.detail-back {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 20px;
  font-size: 14px;
  color: var(--text-secondary);
}

.detail-header {
  margin-bottom: 24px;
}

.detail-title {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 12px;
  line-height: 1.4;
}

.detail-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 14px;
  color: var(--text-secondary);
}

.detail-content {
  font-size: 16px;
  line-height: 1.8;
}

.detail-content h2 {
  font-size: 20px;
  margin: 24px 0 12px;
}

.detail-content h3 {
  font-size: 18px;
  margin: 20px 0 8px;
}

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

.detail-content ul {
  margin: 12px 0;
  padding-left: 24px;
}

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

.detail-content code {
  background: var(--bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 14px;
}

.detail-tags {
  margin-top: 24px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

/* Loading */
.loading {
  text-align: center;
  padding: 40px;
  color: var(--text-secondary);
}

.spinner {
  display: inline-block;
  width: 24px;
  height: 24px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Empty State */
.empty {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 48px;
  margin-bottom: 12px;
}

/* Load More */
.load-more {
  text-align: center;
  padding: 20px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 14px;
  cursor: pointer;
  transition: background 0.2s;
}

.btn:hover {
  background: var(--primary-light);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Responsive */
@media (max-width: 640px) {
  .header-inner {
    padding: 10px 16px;
  }

  .search-box {
    max-width: none;
  }

  .nav-inner {
    padding: 0 16px;
  }

  .main {
    padding: 16px;
  }

  .news-card {
    padding: 12px 16px;
  }

  .detail-title {
    font-size: 20px;
  }
}