/* ============================================================
   课程教学设计能力大赛官网 - 后台管理系统样式
   ============================================================ */
:root{
  --primary:#1a56db;
  --primary-dark:#1245a8;
  --sidebar:#0f1f3d;
  --sidebar-hover:#1a2d52;
  --sidebar-active:#1a56db;
  --text:#1f2937;
  --text-light:#6b7280;
  --border:#e5e7eb;
  --bg:#f1f3f8;
  --white:#fff;
  --green:#059669;
  --red:#dc2626;
  --amber:#d97706;
  --radius:8px;
  --shadow:0 1px 3px rgba(0,0,0,.06),0 1px 2px rgba(0,0,0,.04);
  --shadow-lg:0 10px 30px rgba(0,0,0,.1);
}
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:"PingFang SC","Microsoft YaHei",Arial,sans-serif;font-size:14px;color:var(--text);background:var(--bg)}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}
ul{list-style:none}

/* ===== 登录页 ===== */
.login-page{min-height:100vh;display:flex;align-items:center;justify-content:center;background:linear-gradient(135deg,#0f1f3d 0%,#1245a8 100%);position:relative;overflow:hidden}
.login-page::before{content:"";position:absolute;width:600px;height:600px;border-radius:50%;background:rgba(255,255,255,.04);top:-200px;right:-100px}
.login-page::after{content:"";position:absolute;width:400px;height:400px;border-radius:50%;background:rgba(255,255,255,.03);bottom:-150px;left:-80px}
.login-box{background:#fff;border-radius:16px;box-shadow:0 25px 60px rgba(0,0,0,.3);width:400px;max-width:92vw;padding:44px 38px;position:relative;z-index:2}
.login-logo{text-align:center;margin-bottom:28px}
.login-logo svg{margin-bottom:10px}
.login-logo h1{font-size:21px;color:#13306d;font-weight:700}
.login-logo p{font-size:12px;color:var(--text-light);margin-top:4px}
.login-field{margin-bottom:18px}
.login-field label{display:block;margin-bottom:6px;font-weight:600;font-size:13px;color:#374151}
.login-field input{width:100%;padding:11px 14px;border:1px solid var(--border);border-radius:8px;font-size:14px;transition:all .2s}
.login-field input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(26,86,219,.12)}
.login-btn{width:100%;padding:12px;background:var(--primary);color:#fff;border:none;border-radius:8px;font-size:15px;font-weight:600;cursor:pointer;transition:background .2s}
.login-btn:hover{background:var(--primary-dark)}
.login-error{background:#fef2f2;border:1px solid #fecaca;color:var(--red);padding:10px 14px;border-radius:8px;font-size:13px;margin-bottom:18px}
.login-hint{text-align:center;margin-top:18px;font-size:12px;color:var(--text-light)}
.login-hint a{font-size:12px}

/* ===== 后台框架 ===== */
.admin-wrap{display:flex;min-height:100vh}
.sidebar{width:230px;background:var(--sidebar);position:fixed;top:0;left:0;bottom:0;overflow-y:auto;z-index:100;transition:transform .25s}
.sidebar-logo{padding:20px 22px;color:#fff;display:flex;align-items:center;gap:10px;border-bottom:1px solid rgba(255,255,255,.08)}
.sidebar-logo .logo-text{font-size:16px;font-weight:700;line-height:1.3}
.sidebar-logo .logo-text small{display:block;font-size:11px;font-weight:400;opacity:.6;margin-top:2px}
.sidebar-user{padding:16px 22px;border-bottom:1px solid rgba(255,255,255,.08);color:#a8b3cc;font-size:13px}
.sidebar-user strong{color:#fff;display:block;font-size:14px;margin-bottom:2px}
.nav-section{padding:8px 0}
.nav-section-title{padding:8px 22px 4px;font-size:11px;color:#5a6885;text-transform:uppercase;letter-spacing:1px}
.nav-item{display:flex;align-items:center;gap:10px;padding:11px 22px;color:#a8b3cc;font-size:14px;transition:all .2s;border-left:3px solid transparent}
.nav-item:hover{background:var(--sidebar-hover);color:#fff;text-decoration:none}
.nav-item.active{background:var(--sidebar-active);color:#fff;border-left-color:var(--amber)}
.nav-item .ni{font-size:16px;width:20px;text-align:center}

.main{flex:1;margin-left:230px;min-height:100vh;display:flex;flex-direction:column}
.topbar{height:60px;background:#fff;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 24px;position:sticky;top:0;z-index:50}
.topbar-left{display:flex;align-items:center;gap:16px}
.topbar-left .menu-toggle{display:none;font-size:20px;cursor:pointer;background:none;border:none;color:var(--text)}
.topbar-title{font-size:17px;font-weight:600;color:#13306d}
.topbar-right{display:flex;align-items:center;gap:18px}
.topbar-link{font-size:13px;color:var(--text-light)}
.topbar-link:hover{text-decoration:none;color:var(--primary)}
.user-chip{display:flex;align-items:center;gap:8px}
.user-avatar{width:34px;height:34px;border-radius:50%;background:var(--primary);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:600;font-size:14px}
.content{padding:24px;flex:1}

/* ===== 卡片/统计 ===== */
.card{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--border)}
.card-head{padding:16px 20px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between}
.card-head h3{font-size:16px;color:#13306d;font-weight:600}
.card-body{padding:20px}
.stat-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;margin-bottom:24px}
.stat-card{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--border);padding:20px;display:flex;align-items:center;gap:16px}
.stat-icon{width:54px;height:54px;border-radius:12px;display:flex;align-items:center;justify-content:center;font-size:24px;flex-shrink:0}
.stat-icon.blue{background:#eef4ff;color:#1a56db}
.stat-icon.green{background:#f0fdf4;color:#059669}
.stat-icon.amber{background:#fff5e6;color:#d97706}
.stat-icon.red{background:#fdeaea;color:#dc2626}
.stat-info .num{font-size:26px;font-weight:700;color:#13306d;line-height:1.2}
.stat-info .label{font-size:13px;color:var(--text-light);margin-top:2px}
.stat-info .delta{font-size:12px;margin-top:4px}
.stat-info .delta.up{color:var(--green)}
.stat-info .delta.down{color:var(--red)}

/* ===== 表格 ===== */
.table-wrap{overflow-x:auto;background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--border)}
table.admin-table{width:100%;border-collapse:collapse}
table.admin-table th{background:#f8fafc;padding:12px 16px;text-align:left;font-weight:600;font-size:13px;color:#475569;border-bottom:2px solid var(--border);white-space:nowrap}
table.admin-table td{padding:12px 16px;border-bottom:1px solid var(--border);font-size:14px}
table.admin-table tr:hover td{background:#fafbfc}
table.admin-table tr:last-child td{border-bottom:none}
.td-id{color:var(--text-light);font-family:monospace;font-size:13px}
.td-title{font-weight:600;color:#13306d}
.td-time{color:var(--text-light);font-size:13px;white-space:nowrap}

/* ===== 状态标签 ===== */
.tag{display:inline-block;padding:3px 10px;border-radius:12px;font-size:12px;font-weight:500;line-height:1.5}
.tag-blue{background:#eef4ff;color:#1a56db}
.tag-green{background:#f0fdf4;color:#059669}
.tag-amber{background:#fff5e6;color:#d97706}
.tag-red{background:#fdeaea;color:#dc2626}
.tag-gray{background:#f3f4f6;color:#6b7280}

/* ===== 按钮 ===== */
.btn{display:inline-block;padding:8px 16px;border:none;border-radius:6px;font-size:13px;font-weight:500;cursor:pointer;transition:all .2s;text-decoration:none;line-height:1.4}
.btn:hover{text-decoration:none}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-dark);color:#fff}
.btn-success{background:var(--green);color:#fff}
.btn-success:hover{background:#047857;color:#fff}
.btn-warning{background:var(--amber);color:#fff}
.btn-danger{background:var(--red);color:#fff}
.btn-danger:hover{background:#b91c1c;color:#fff}
.btn-outline{background:#fff;color:var(--text);border:1px solid var(--border)}
.btn-outline:hover{border-color:var(--primary);color:var(--primary)}
.btn-sm{padding:5px 11px;font-size:12px}
.btn-block{display:block;width:100%;text-align:center}

/* ===== 表单 ===== */
.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.form-group{margin-bottom:16px}
.form-group label{display:block;margin-bottom:6px;font-weight:600;font-size:13px;color:#374151}
.form-group label .req{color:var(--red)}
.form-group input,.form-group select,.form-group textarea{width:100%;padding:9px 12px;border:1px solid var(--border);border-radius:6px;font-size:14px;font-family:inherit;transition:all .2s;background:#fff}
.form-group input:focus,.form-group select:focus,.form-group textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(26,86,219,.12)}
.form-group textarea{resize:vertical;min-height:120px}
.form-group .hint{font-size:12px;color:var(--text-light);margin-top:4px}
.form-actions{display:flex;gap:10px;margin-top:20px;padding-top:16px;border-top:1px solid var(--border)}

/* ===== 工具栏 ===== */
.toolbar{display:flex;align-items:center;justify-content:space-between;margin-bottom:18px;flex-wrap:wrap;gap:12px}
.toolbar-left{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.filter-bar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-bottom:16px}
.filter-bar select,.filter-bar input{padding:7px 12px;border:1px solid var(--border);border-radius:6px;font-size:13px}

/* ===== 搜索 ===== */
.search-box{position:relative;display:inline-block}
.search-box input{padding:8px 12px 8px 34px;border:1px solid var(--border);border-radius:6px;font-size:13px;width:240px}
.search-box input:focus{outline:none;border-color:var(--primary)}
.search-box .ico{position:absolute;left:10px;top:50%;transform:translateY(-50%);color:var(--text-light);font-size:14px}

/* ===== 分页 ===== */
.pagination{display:flex;gap:5px;justify-content:center;margin-top:20px;flex-wrap:wrap}
.pagination a,.pagination span{display:inline-block;padding:6px 12px;border:1px solid var(--border);border-radius:5px;font-size:13px;background:#fff;color:var(--text)}
.pagination a:hover{border-color:var(--primary);color:var(--primary);text-decoration:none}
.pagination .active{background:var(--primary);color:#fff;border-color:var(--primary)}
.pagination .disabled{opacity:.5;pointer-events:none}

/* ===== 详情 ===== */
.detail-list{display:grid;grid-template-columns:140px 1fr;gap:0;font-size:14px}
.detail-list .dl-label{padding:12px 16px;background:#f8fafc;border-bottom:1px solid var(--border);color:var(--text-light);font-weight:500}
.detail-list .dl-value{padding:12px 16px;border-bottom:1px solid var(--border)}

/* ===== 空状态 ===== */
.empty{text-align:center;padding:50px 20px;color:var(--text-light)}
.empty .ico{font-size:48px;margin-bottom:12px;opacity:.4}

/* ===== 提示 ===== */
.alert{padding:12px 16px;border-radius:6px;margin-bottom:16px;font-size:14px}
.alert-success{background:#f0fdf4;border:1px solid #bbf7d0;color:#15803d}
.alert-error{background:#fef2f2;border:1px solid #fecaca;color:#b91c1c}
.alert-info{background:#eff6ff;border:1px solid #bfdbfe;color:#1e40af}

/* ===== 响应式 ===== */
@media (max-width:992px){
  .stat-grid{grid-template-columns:1fr 1fr}
  .form-grid{grid-template-columns:1fr}
}
@media (max-width:768px){
  .sidebar{transform:translateX(-100%)}
  .sidebar.show{transform:translateX(0)}
  .main{margin-left:0}
  .topbar-left .menu-toggle{display:block}
  .stat-grid{grid-template-columns:1fr}
  .search-box input{width:160px}
}

/* ===== 附件列表 ===== */
.attach-list{display:flex;flex-direction:column;gap:8px}
.attach-item{display:flex;align-items:center;gap:12px;background:#fff;border:1px solid var(--border);border-radius:8px;padding:10px 14px}
.attach-item .ai-icon{width:38px;height:38px;border-radius:8px;display:flex;align-items:center;justify-content:center;color:#fff;font-size:10px;font-weight:700;flex-shrink:0}
.attach-item .ai-info{flex:1;min-width:0}
.attach-item .ai-name{font-size:13px;font-weight:500;color:var(--text);overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.attach-item .ai-meta{font-size:11px;color:var(--text-light);margin-top:2px}
.tag-blue{background:#dbeafe;color:#1a56db}
@media(max-width:768px){
  .attach-item{flex-wrap:wrap}
}