/* =========================
   1. CSS 变量
   ========================= */
:root {
  --bg: #f5f7fa;
  --text: #222;
  --muted: #666;
  --border: #e5e7eb;
  --card-bg: rgba(255, 255, 255, 0.65);
  --accent: #0077cc;
  --radius: 12px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

[data-theme="dark"] {
  --bg: #0b0f1a;
  --text: #e6e6e6;
  --muted: #999;
  --border: #2a2d36;
  --card-bg: rgba(20, 24, 40, 0.65);
  --accent: #4db8ff;
}

/* =========================
   2. 背景（渐变 + 噪点）
   ========================= */
body {
  margin: 0;
  font-family: var(--font);
  color: var(--text);
  background:
    linear-gradient(135deg, #f5f7fa, #e4ecf7),
    url(images/background.jpg);
  background-size: cover;
  transition: background 0.3s, color 0.3s;
}

[data-theme="dark"] body {
  background:
    linear-gradient(135deg, #0b0f1a, #14182a), url("images/background.jpg");
}
   

/* =========================
   3. 布局
   ========================= */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 24px;
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 48px;
}

@media (max-width: 900px) {
  .container {
    grid-template-columns: 1fr;
  }
}

/* =========================
   4. 侧边栏
   ========================= */
.sidebar {
  position: sticky;
  top: 40px;
}

.sidebar h1 {
  margin: 0;
  font-size: 1.6rem;
}

.sidebar p {
  color: var(--muted);
  margin: 8px 0 20px;
}

.sidebar nav a {
  display: block;
  margin-bottom: 10px;
}

/* =========================
   5. 文章卡片（玻璃拟态）
   ========================= */
.post-card {
  backdrop-filter: blur(14px);
  background: var(--card-bg);
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 32px;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease;
}

.post-card:hover {
  transform: translateY(-4px);
}

.post-meta {
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 10px;
}

/* =========================
   6. 标签
   ========================= */
.tags {
  margin-top: 12px;
}

.tag {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  margin-right: 6px;
}

/* =========================
   7. 页脚
   ========================= */
footer {
  text-align: center;
  padding: 30px 0;
  font-size: 0.85rem;
  color: var(--muted);
  border-top: 1px solid var(--border);
  margin-top: 60px;
}

/* =========================
   8. 主题切换按钮
   ========================= */
.theme-toggle {
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--card-bg);
  cursor: pointer;
  font-size: 1.2rem;
}