/* === DESIGN.md (内嵌于页面) === */
:root {
  /* 主色 */
  --color-primary: #2563EB;
  --color-primary-dark: #1E40AF;
  --color-primary-light: #DBEAFE;
  --color-primary-50: #EFF6FF;

  /* 品牌色 */
  --color-brand: #0F766E;

  /* 强调色 */
  --color-accent: #EA580C;
  --color-accent-light: #FFEDD5;
  --color-accent-bg: #FFF7ED;

  /* 中性灰 */
  --color-gray-50: #F9FAFB;
  --color-gray-100: #F3F4F6;
  --color-gray-200: #E5E7EB;
  --color-gray-300: #D1D5DB;
  --color-gray-400: #9CA3AF;
  --color-gray-500: #6B7280;
  --color-gray-600: #4B5563;
  --color-gray-700: #374151;
  --color-gray-800: #1F2937;
  --color-gray-900: #111827;

  /* 表面与边框 */
  --color-surface: #FFFFFF;
  --color-bg: #F5F7FA;
  --color-border: #E5E7EB;
  --color-border-light: #F0F2F5;

  /* 语义色 */
  --color-success: #059669;
  --color-success-bg: #ECFDF5;
  --color-warning: #D97706;
  --color-warning-bg: #FFFBEB;
  --color-danger: #DC2626;
  --color-danger-bg: #FEF2F2;
  --color-info: #0891B2;
  --color-info-bg: #ECFEFF;

  /* 阴影色 */
  --shadow-color: rgba(15, 23, 42, 0.08);
  --shadow-color-strong: rgba(15, 23, 42, 0.12);

  /* 字号 */
  --fs-display: 28px;
  --fs-h1: 22px;
  --fs-h2: 18px;
  --fs-h3: 16px;
  --fs-body: 14px;
  --fs-small: 12px;
  --fs-nano: 11px;

  /* 间距 */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;

  /* 圆角 */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 18px;

  /* 阴影 */
  --shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 12px 28px rgba(15, 23, 42, 0.12);
}

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

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei",
    "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--color-gray-900);
  background: var(--color-bg);
  font-size: var(--fs-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: 0; background: transparent; }

/* ============== 顶部 Header ============== */
.app-header {
  background: linear-gradient(135deg, #FFFFFF 0%, #F8FAFF 100%);
  border-bottom: 1px solid var(--color-border-light);
  padding: var(--space-5) 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  background: rgba(255, 255, 255, 0.85);
}

.header-inner {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex: 0 0 auto;
}

.brand-logo {
  width: 48px; height: 48px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  display: flex; align-items: center; justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: -0.5px;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
  position: relative;
  overflow: hidden;
}
.brand-logo::after {
  content: '';
  position: absolute;
  top: -50%; right: -50%;
  width: 100%; height: 100%;
  background: radial-gradient(circle, rgba(255,255,255,0.3) 0%, transparent 60%);
}

.brand-text h1 {
  font-size: var(--fs-display);
  font-weight: 700;
  color: var(--color-gray-900);
  letter-spacing: -0.5px;
  line-height: 1.2;
}
.brand-text h1 .accent { color: var(--color-primary); }
.brand-text p {
  font-size: var(--fs-small);
  color: var(--color-gray-500);
  margin-top: 4px;
  max-width: 520px;
}

.header-search {
  flex: 1;
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
  align-items: center;
}

.search-box {
  position: relative;
  flex: 0 1 340px;
}
.search-box input {
  width: 100%;
  padding: 10px 16px 10px 38px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: var(--fs-body);
  background: white;
  outline: none;
  transition: all 0.2s;
}
.search-box input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}
.search-box::before {
  content: '🔍';
  position: absolute;
  left: 14px; top: 50%;
  transform: translateY(-50%);
  font-size: 14px;
  opacity: 0.6;
}

.btn-primary {
  padding: 10px 20px;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: white;
  border-radius: 999px;
  font-weight: 500;
  font-size: var(--fs-body);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
  transition: transform 0.15s, box-shadow 0.15s;
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 4px 12px rgba(37, 99, 235, 0.4); }

/* ============== 主体布局 ============== */
.app-main {
  max-width: 1400px;
  margin: var(--space-6) auto var(--space-8);
  padding: 0 var(--space-6);
  display: grid;
  grid-template-columns: minmax(0, 1fr) 340px;
  gap: var(--space-6);
  align-items: start;
}

/* ============== 主区 今日头条 ============== */
.feed-section {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--space-5);
}
.section-head h2 {
  font-size: var(--fs-h1);
  font-weight: 700;
  color: var(--color-gray-900);
}
.section-head .subtitle {
  font-size: var(--fs-small);
  color: var(--color-gray-500);
  margin-top: 4px;
}
.head-actions { display: flex; align-items: center; gap: 12px; flex: 0 0 auto; }
.btn-pill {
  padding: 7px 14px;
  border: 1px solid var(--color-gray-200);
  border-radius: 999px;
  font-size: var(--fs-small);
  color: var(--color-gray-600);
  background: white;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: all 0.15s;
}
.btn-pill:hover { border-color: var(--color-primary); color: var(--color-primary); }

.score-bar {
  background: var(--color-gray-50);
  border: 1px dashed var(--color-gray-200);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--fs-small);
  color: var(--color-gray-600);
  margin-bottom: var(--space-5);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* 卡片 */
.feed-card {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-4);
  padding: var(--space-5) 0;
  border-bottom: 1px solid var(--color-border-light);
  cursor: pointer;
  transition: background 0.15s;
  padding-left: var(--space-3);
  padding-right: var(--space-3);
  margin: 0 calc(var(--space-3) * -1);
  border-radius: var(--radius-md);
}
.feed-card:hover { background: var(--color-primary-50); }
.feed-card:last-child { border-bottom: 0; }

.feed-content { min-width: 0; }
.feed-title {
  font-size: var(--fs-h3);
  font-weight: 600;
  color: var(--color-gray-900);
  margin-bottom: 8px;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.feed-card:hover .feed-title { color: var(--color-primary); }

.feed-summary {
  color: var(--color-gray-600);
  font-size: var(--fs-body);
  line-height: 1.7;
  margin-bottom: var(--space-3);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.feed-meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  font-size: var(--fs-small);
  color: var(--color-gray-500);
}

.tag-impact {
  background: var(--color-accent-bg);
  color: var(--color-accent);
  border: 1px solid var(--color-accent-light);
  padding: 2px 10px;
  border-radius: 4px;
  font-weight: 500;
}

.tag-cat {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 8px;
  background: var(--color-primary-50);
  color: var(--color-primary);
  border-radius: 4px;
  font-size: var(--fs-nano);
  font-weight: 500;
}

.tag-link {
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: 2px;
}
.tag-link:hover { text-decoration: underline; }

.toggle {
  color: var(--color-primary);
  font-size: var(--fs-small);
  margin-left: auto;
}

/* 影响评分 */
.feed-score {
  text-align: right;
  flex-shrink: 0;
  padding-left: var(--space-4);
}
.feed-score .label {
  font-size: var(--fs-nano);
  color: var(--color-gray-400);
  margin-bottom: 4px;
  letter-spacing: 0.5px;
}
.feed-score .num {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-primary);
  font-variant-numeric: tabular-nums;
  letter-spacing: -1px;
  line-height: 1;
}
.feed-score .num.very-high { color: var(--color-danger); }
.feed-score .num.high { color: var(--color-accent); }

/* 加载更多 */
.load-more {
  text-align: center;
  margin-top: var(--space-5);
  padding-top: var(--space-5);
  border-top: 1px dashed var(--color-gray-200);
}
.load-more button {
  padding: 10px 32px;
  border: 1px solid var(--color-gray-200);
  border-radius: 999px;
  color: var(--color-gray-600);
  background: white;
  font-size: var(--fs-body);
  transition: all 0.15s;
}
.load-more button:hover { border-color: var(--color-primary); color: var(--color-primary); }

/* ============== 侧栏 ============== */
.sidebar {
  position: sticky;
  top: 110px;
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--space-5);
  box-shadow: var(--shadow-sm);
}

.sidebar-head h3 {
  font-size: var(--fs-h2);
  font-weight: 700;
  display: inline-block;
}
.sidebar-head .hint {
  font-size: var(--fs-small);
  color: var(--color-gray-500);
  margin-left: var(--space-3);
}
.sidebar-head { margin-bottom: var(--space-4); }

.stats-source {
  display: flex;
  gap: var(--space-2);
  background: var(--color-gray-100);
  padding: 4px;
  border-radius: 999px;
  margin-bottom: var(--space-4);
  width: fit-content;
}
.stats-source button {
  padding: 6px 14px;
  border-radius: 999px;
  font-size: var(--fs-small);
  color: var(--color-gray-600);
  transition: all 0.15s;
}
.stats-source button.active {
  background: var(--color-primary);
  color: white;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.3);
}

.stats-desc {
  font-size: var(--fs-small);
  color: var(--color-gray-500);
  margin-bottom: var(--space-4);
  line-height: 1.6;
}

/* 分类块 */
.cat-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3);
}

.cat-card {
  padding: var(--space-3);
  border-radius: var(--radius-md);
  background: var(--color-gray-50);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.15s;
  position: relative;
}
.cat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.cat-name {
  font-size: var(--fs-small);
  color: var(--color-gray-700);
  font-weight: 500;
  margin-bottom: 6px;
  line-height: 1.4;
}
.cat-num {
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -1px;
  font-variant-numeric: tabular-nums;
  line-height: 1;
}
.cat-tag {
  font-size: var(--fs-nano);
  color: var(--color-gray-400);
  margin-top: 4px;
}

/* 热度色阶（从冷蓝到热橙到红） */
.cat-card.cool { background: #EFF6FF; border-color: #DBEAFE; }
.cat-card.cool .cat-num { color: #2563EB; }
.cat-card.warm { background: #FFF7ED; border-color: #FED7AA; }
.cat-card.warm .cat-num { color: #EA580C; }
.cat-card.hot { background: #FEF2F2; border-color: #FECACA; }
.cat-card.hot .cat-num { color: #DC2626; }
.cat-card.mid { background: #F0FDF4; border-color: #BBF7D0; }
.cat-card.mid .cat-num { color: #059669; }
.cat-card.dim { background: var(--color-gray-50); border-color: var(--color-gray-200); }
.cat-card.dim .cat-num { color: var(--color-gray-500); }

/* ============== 响应式 ============== */
@media (max-width: 1024px) {
  .app-main { grid-template-columns: 1fr; }
  .sidebar { position: static; }
}
@media (max-width: 640px) {
  .header-inner { flex-direction: column; align-items: flex-start; gap: var(--space-3); }
  .header-search { width: 100%; }
  .search-box { flex: 1; width: 100%; }
  .feed-card { grid-template-columns: 1fr; }
  .feed-score { text-align: left; padding-left: 0; }
  .feed-score .num { font-size: 22px; }
  .cat-grid { grid-template-columns: 1fr 1fr; }
  .brand-text h1 { font-size: 20px; }
}