/* ============================================================
   博客系统前端样式 —— 现代简洁风格
   使用 CSS 变量，便于后端 PHP 模板注入主题色
   ============================================================ */

:root {
  --color-bg: #f7f8fa;
  --color-surface: #ffffff;
  --color-text: #1f2329;
  --color-text-muted: #6b7280;
  --color-primary: #4f46e5;        /* 主题色，后端可覆盖 */
  --color-primary-hover: #4338ca;
  --color-border: #e5e7eb;
  --color-danger: #ef4444;
  --radius: 10px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.06);
  --shadow-md: 0 6px 20px rgba(0,0,0,.08);
  --max-width: 960px;
  --font-sans: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","PingFang SC","Microsoft YaHei",sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 20px; }

/* ---------- 顶部导航 ---------- */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky; top: 0; z-index: 50;
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.logo { font-size: 20px; font-weight: 700; color: var(--color-text); }
.nav a { margin-left: 18px; color: var(--color-text-muted); font-size: 15px; }
.nav a:hover { color: var(--color-primary); text-decoration: none; }

/* ---------- 通用按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 9px 18px; border: 1px solid transparent; border-radius: var(--radius);
  font-size: 14px; cursor: pointer; background: var(--color-primary); color: #fff;
  transition: background .15s ease;
}
.btn:hover { background: var(--color-primary-hover); text-decoration: none; }
.btn-outline { background: transparent; color: var(--color-primary); border-color: var(--color-primary); }
.btn-outline:hover { background: var(--color-primary); color: #fff; }

/* ---------- 文章卡片网格 ---------- */
.post-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px,1fr)); gap: 20px; margin: 30px 0; }
.post-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow-sm);
  transition: transform .15s ease, box-shadow .15s ease; display: flex; flex-direction: column;
}
.post-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.post-card h2 { margin: 0 0 10px; font-size: 18px; }
.post-card .excerpt { color: var(--color-text-muted); font-size: 14px; flex: 1; }
.post-meta { margin-top: 14px; font-size: 13px; color: var(--color-text-muted); display: flex; gap: 12px; flex-wrap: wrap; }
.tag { background: var(--color-bg); border: 1px solid var(--color-border); padding: 2px 8px; border-radius: 999px; font-size: 12px; }

/* ---------- 分页 ---------- */
.pagination { display: flex; gap: 8px; justify-content: center; margin: 30px 0 50px; }
.pagination a, .pagination span {
  padding: 7px 13px; border: 1px solid var(--color-border); border-radius: 8px;
  color: var(--color-text); background: var(--color-surface); font-size: 14px;
}
.pagination .current { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }

/* ---------- 文章详情 ---------- */
.article { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 32px; margin: 30px 0; box-shadow: var(--shadow-sm); }
.article h1 { margin-top: 0; }
.article .content { margin-top: 20px; }
.article .content img { max-width: 100%; border-radius: 8px; }
.article pre { background: #0f172a; color: #e2e8f0; padding: 16px; border-radius: 8px; overflow:auto; }
.article code { background: var(--color-bg); padding: 2px 6px; border-radius: 4px; font-size: 13px; }

/* ---------- 登录 / 注册 ---------- */
.auth-wrap { max-width: 400px; margin: 60px auto; background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 32px; box-shadow: var(--shadow-sm); }
.auth-wrap h2 { margin-top: 0; text-align: center; }
.field { margin-bottom: 16px; }
.field label { display: block; font-size: 14px; margin-bottom: 6px; color: var(--color-text-muted); }
.field input, .field textarea {
  width: 100%; padding: 10px 12px; border: 1px solid var(--color-border);
  border-radius: 8px; font-size: 14px; font-family: inherit;
}
.field input:focus, .field textarea:focus { outline: none; border-color: var(--color-primary); }
.alert { padding: 10px 14px; border-radius: 8px; margin-bottom: 16px; font-size: 14px; }
.alert-error { background: #fee2e2; color: var(--color-danger); }
.alert-success { background: #dcfce7; color: #16a34a; }

/* ---------- 评论 ---------- */
.comments { margin-top: 40px; }
.comment { border-top: 1px solid var(--color-border); padding: 14px 0; }
.comment .author { font-weight: 600; font-size: 14px; }
.comment .date { font-size: 12px; color: var(--color-text-muted); margin-left: 8px; }

/* ---------- 后台管理 ---------- */
.admin-table { width: 100%; border-collapse: collapse; background: var(--color-surface); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow-sm); }
.admin-table th, .admin-table td { padding: 12px 14px; border-bottom: 1px solid var(--color-border); text-align: left; font-size: 14px; }
.admin-table th { background: var(--color-bg); }

/* ---------- 新增：导航布局 / 分类条 / 页脚 / 杂项 ---------- */
.nav-bar { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.nav .user { color: var(--color-text-muted); font-size: 14px; margin-left: 14px; }
.cat-bar { display: flex; flex-wrap: wrap; gap: 8px; margin: 26px 0 4px; }
.cat-bar .tag.active { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.write-wrap, .error-wrap { max-width: 720px; margin: 40px auto; background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow-sm); }
.error-wrap { text-align: center; }
.login-tip { color: var(--color-text-muted); font-size: 14px; }
.empty { color: var(--color-text-muted); text-align: center; padding: 40px 0; }
.switch { text-align: center; margin-top: 16px; font-size: 14px; color: var(--color-text-muted); }
.site-footer { border-top: 1px solid var(--color-border); margin-top: 40px; padding: 24px 0; color: var(--color-text-muted); font-size: 13px; text-align: center; }

/* ---------- 响应式 ---------- */
@media (max-width: 600px) {
  .site-header .container { height: 54px; }
  .nav a { margin-left: 12px; font-size: 14px; }
  .post-grid { grid-template-columns: 1fr; }
  .article { padding: 20px; }
  .auth-wrap { margin: 30px 16px; }
}