:root {
  --bg: #f4f6fa;
  --sidebar: #1f2733;
  --sidebar-hover: #2b3543;
  --accent: #2f6feb;
  --text: #2c3540;
  --muted: #7a8699;
  --card: #ffffff;
  --border: #e4e9f0;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: "Segoe UI", "Microsoft YaHei", sans-serif; background: var(--bg); color: var(--text); }
.layout { display: flex; min-height: 100vh; }
.sidebar { width: 216px; background: var(--sidebar); color: #cfd8e3; flex-shrink: 0; display: flex; flex-direction: column; }
.brand { padding: 20px 18px; font-size: 16px; font-weight: 600; color: #fff; border-bottom: 1px solid #2c3745; }
.nav { flex: 1; padding: 12px 0; }
.nav-item { display: flex; align-items: center; gap: 10px; padding: 12px 18px; color: #cfd8e3; text-decoration: none; font-size: 14px; }
.nav-item:hover { background: var(--sidebar-hover); color: #fff; }
.nav-item.active { background: var(--accent); color: #fff; }
.nav-icon { width: 18px; text-align: center; }
.sidebar-foot { padding: 14px 18px; border-top: 1px solid #2c3745; }
.sidebar-foot a { color: #9fb0c4; text-decoration: none; font-size: 13px; }
.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.topbar { background: var(--card); border-bottom: 1px solid var(--border); padding: 16px 24px; display: flex; justify-content: space-between; align-items: center; }
.topbar-title { font-size: 17px; font-weight: 600; }
.topbar-user { font-size: 13px; color: var(--muted); }
.content { padding: 24px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 18px 20px; margin-bottom: 18px; }
.card h3 { font-size: 15px; margin-bottom: 12px; }
.stat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 16px; }
.stat { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 18px; }
.stat .num { font-size: 26px; font-weight: 700; }
.stat .label { font-size: 13px; color: var(--muted); margin-top: 4px; }
table.list { width: 100%; border-collapse: collapse; font-size: 14px; }
table.list th, table.list td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; }
table.list th { color: var(--muted); font-weight: 600; background: #fafbfd; }
.muted { color: var(--muted); font-size: 13px; }
.btn { display: inline-block; padding: 8px 16px; border-radius: 6px; border: 1px solid var(--border); background: #fff; color: var(--text); cursor: pointer; font-size: 13px; text-decoration: none; }
.btn-primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.tag { display: inline-block; padding: 2px 10px; border-radius: 10px; font-size: 12px; }
.tag-on { background: #e6f4ea; color: #1e7e34; }
.tag-off { background: #fdecea; color: #c0392b; }
/* 登录页 */
.login-wrap { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: linear-gradient(135deg, #1f2733, #2f6feb); }
.login-box { background: #fff; border-radius: 10px; padding: 36px 32px; width: 340px; }
.login-box h2 { font-size: 18px; text-align: center; margin-bottom: 24px; }
.login-box label { font-size: 13px; color: var(--muted); display: block; margin-bottom: 6px; }
.login-box input { width: 100%; padding: 10px 12px; border: 1px solid var(--border); border-radius: 6px; font-size: 14px; margin-bottom: 16px; }
.login-box button { width: 100%; padding: 11px; background: var(--accent); color: #fff; border: none; border-radius: 6px; font-size: 14px; cursor: pointer; }
.error { color: #c0392b; font-size: 13px; margin-bottom: 12px; }
@media (max-width: 768px) {
  .layout { flex-direction: column; }
  .sidebar { width: 100%; }
  .nav { display: flex; overflow-x: auto; }
}

/* ===== 用户管理扩展 ===== */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px 20px; }
.form-grid label { font-size: 13px; color: var(--muted); display: block; margin-bottom: 4px; }
.form-grid input { width: 100%; padding: 9px 12px; border: 1px solid var(--border); border-radius: 6px; font-size: 14px; margin-top: 4px; }
.form-grid input:focus { border-color: var(--accent); outline: none; }
.op { color: var(--accent); text-decoration: none; font-size: 13px; margin-right: 10px; }
.op.on { font-weight: 700; }
.op-btn { border: 1px solid var(--border); background: #fff; color: var(--text); border-radius: 5px; padding: 4px 10px; font-size: 12px; cursor: pointer; margin-right: 6px; }
.op-btn:hover { border-color: var(--accent); color: var(--accent); }
.op-del { color: #c0392b; border-color: #e7b7b4; }
.op-del:hover { color: #fff; background: #c0392b; border-color: #c0392b; }
@media (max-width: 768px) { .form-grid { grid-template-columns: 1fr; } }

/* ===== 留言管理扩展 ===== */
.tag-pending { background: #f0f2f5; color: #7a8699; }
.tag-replied { background: #e6f4ea; color: #1e7e34; }
.tag-done { background: #e8f0fe; color: #2f6feb; }
/* ===== 新版扩展：提示条 / 占位菜单 ===== */
.flash-ok { background: #e8f5e9; color: #2e7d32; border: 1px solid #bfe0c1; padding: 10px 14px; border-radius: 6px; margin-bottom: 14px; font-size: 13px; }
.flash-err { background: #fdecea; color: #c0392b; border: 1px solid #e7b7b4; padding: 10px 14px; border-radius: 6px; margin-bottom: 14px; font-size: 13px; }
.nav-disabled { opacity: .55; cursor: not-allowed; }
.soon { margin-left: auto; font-size: 11px; color: #8fa0b5; }
.num-sm { font-size: 17px; padding-top: 7px; font-weight: 600; }