/* ===== 后台管理 / 学生端 共用样式 ===== */
:root{
  --primary:#4f46e5;--primary-600:#4338ca;--primary-50:#eef2ff;
  --bg:#f5f6fa;--surface:#fff;--text:#1f2333;--muted:#6b7280;--border:#e6e8ef;
  --green:#16a34a;--green-50:#ecfdf3;--amber:#f59e0b;--amber-50:#fffbeb;--red:#dc2626;--red-50:#fef2f2;
  --radius:14px;--shadow:0 1px 2px rgba(16,24,40,.05),0 8px 24px -12px rgba(16,24,40,.18);
}
*{box-sizing:border-box}
body.portal{margin:0;background:var(--bg);color:var(--text);
  font-family:"PingFang SC","Microsoft YaHei",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;font-size:14px;line-height:1.5}
a{color:inherit;text-decoration:none}
h1,h2,h3,h4{margin:0}

.p-topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:14px 22px;background:#fff;border-bottom:1px solid var(--border);position:sticky;top:0;z-index:10}
.p-brand{display:flex;align-items:center;gap:12px;font-weight:600}
.p-logo{width:36px;height:36px;border-radius:11px;background:linear-gradient(135deg,#6366f1,#4f46e5);color:#fff;display:grid;place-items:center;font-weight:700}
.p-actions{display:flex;gap:8px;flex-wrap:wrap;align-items:center}

.btn{border:1px solid transparent;border-radius:10px;padding:9px 14px;font:inherit;font-size:13px;cursor:pointer;
  display:inline-flex;align-items:center;gap:6px;transition:.15s;white-space:nowrap;background:#fff}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-600)}
.btn-ghost{border-color:var(--border);color:var(--text)}
.btn-ghost:hover{background:var(--bg)}
.btn-danger{border-color:#f3c4c4;color:var(--red)}
.btn-danger:hover{background:var(--red-50)}
.btn-sm{padding:6px 10px;font-size:12px}
.icon-btn{border:none;background:transparent;font-size:16px;cursor:pointer;color:var(--muted);width:30px;height:30px;border-radius:8px}
.icon-btn:hover{background:var(--bg);color:var(--text)}

.input,.textarea,select.input{width:100%;border:1px solid var(--border);border-radius:10px;padding:9px 12px;font:inherit;color:var(--text);background:#fff;outline:none;transition:.15s}
.input:focus,.textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px var(--primary-50)}
.textarea{resize:vertical;line-height:1.6}
.field{margin-bottom:12px}
.field>label{display:block;font-size:12px;color:var(--muted);margin-bottom:5px}
.row-actions{display:flex;gap:10px;flex-wrap:wrap}

.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px}
.card h3{font-size:15px;margin-bottom:12px;display:flex;align-items:center;justify-content:space-between}
.muted{color:var(--muted);font-size:12px}
.pill{display:inline-block;padding:2px 9px;border-radius:999px;font-size:12px;font-weight:600}
.pill.good{background:var(--green-50);color:var(--green)}
.pill.warn{background:var(--amber-50);color:var(--amber)}
.pill.gray{background:#f1f2f6;color:#6b7280}

/* 后台布局 */
.admin-wrap{display:grid;grid-template-columns:280px 1fr;gap:18px;padding:18px 22px 60px;max-width:1400px;margin:0 auto}
.class-list{list-style:none;margin:0;padding:0}
.class-item{border:1px solid var(--border);border-radius:12px;padding:12px;margin-bottom:10px;cursor:pointer;transition:.15s;background:#fff}
.class-item:hover{border-color:#c7cbd8}
.class-item.active{border-color:var(--primary);box-shadow:0 0 0 3px var(--primary-50)}
.class-item .ci-name{font-weight:600;display:flex;align-items:center;justify-content:space-between;gap:8px}
.class-item .ci-meta{font-size:12px;color:var(--muted);margin-top:6px;display:flex;gap:12px}
.admin-main{display:flex;flex-direction:column;gap:18px;min-width:0}

.stu-table{width:100%;border-collapse:collapse;font-size:13px}
.stu-table th,.stu-table td{padding:9px 10px;border-bottom:1px solid var(--border);text-align:left}
.stu-table th{color:var(--muted);font-weight:600;font-size:12px}
.stu-table tr:hover td{background:#fafbff}
.stu-scroll{max-height:420px;overflow:auto;border:1px solid var(--border);border-radius:12px}
.table-tools{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-bottom:12px}
.table-tools .input{max-width:240px}

.qr-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:14px}
.qr-cell{border:1px solid var(--border);border-radius:12px;padding:12px;text-align:center;background:#fff}
.qr-cell img{width:100%;max-width:130px;height:auto}
.qr-cell .qc-title{font-size:12px;font-weight:600;margin-bottom:6px}
.qr-cell .qc-link{font-size:11px;color:var(--muted);word-break:break-all;margin-top:6px;max-height:32px;overflow:hidden}

.toast{position:fixed;left:50%;bottom:26px;transform:translate(-50%,20px);background:#0f172a;color:#fff;padding:10px 18px;border-radius:10px;font-size:13px;opacity:0;visibility:hidden;transition:.25s;z-index:80}
.toast.show{opacity:1;visibility:visible;transform:translate(-50%,0)}
.toast.err{background:var(--red)}.toast.ok{background:var(--green)}

/* 学生端 */
.stu-page{max-width:640px;margin:0 auto;padding:28px 18px 60px}
.stu-header{text-align:center;margin-bottom:20px}
.stu-header .badge{display:inline-block;background:var(--primary-50);color:var(--primary-600);padding:4px 12px;border-radius:999px;font-size:12px;font-weight:600;margin-bottom:10px}
.stu-header h1{font-size:22px}
.stu-header p{color:var(--muted);font-size:13px;margin-top:6px}
.dropzone{border:1.6px dashed #cbd0dc;border-radius:12px;padding:26px;text-align:center;cursor:pointer;background:#fbfbfd;transition:.15s}
.dropzone:hover,.dropzone.drag{border-color:var(--primary);background:var(--primary-50)}
.dropzone .dz-ico{font-size:32px}
.dropzone p{font-size:13px;margin-top:6px}
.dropzone small{color:var(--muted);font-size:11px}
.thumbs{display:flex;flex-wrap:wrap;gap:10px;margin-top:12px}
.thumb{position:relative;width:88px;height:88px;border-radius:10px;overflow:hidden;border:1px solid var(--border);background:#fff}
.thumb img{width:100%;height:100%;object-fit:cover}
.thumb button{position:absolute;top:4px;right:4px;border:none;background:rgba(0,0,0,.6);color:#fff;width:20px;height:20px;border-radius:50%;cursor:pointer;font-size:11px}
.meta-row{display:flex;justify-content:space-between;font-size:12px;color:var(--muted);margin-top:8px}
.success-card{text-align:center;padding:28px 18px}
.success-card .ok-ico{font-size:44px}
.success-card h2{margin:10px 0 6px}
.score-hint{font-size:12px;color:var(--muted);margin-top:10px}
.bar{height:8px;border-radius:999px;background:#eef0f5;overflow:hidden;margin-top:6px}
.bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,#818cf8,#4f46e5);transition:width .4s}
@media (max-width:820px){.admin-wrap{grid-template-columns:1fr}}