:root{
  --bg:#f4f6fb;--card:#fff;--ink:#16203a;--muted:#6b7895;--line:#e4e9f3;
  --blue:#3b6cf6;--blue-d:#2b53c8;--blue-l:#eef3ff;
  --green:#0f8a5f;--green-l:#e9f9f1;--red:#cf3f4b;--red-l:#fdeff0;
  --amber:#9a6400;--amber-l:#fff6e2;
  --radius:18px;--shadow:0 8px 28px rgba(24,42,90,.07);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:"PingFang SC","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;line-height:1.5;-webkit-tap-highlight-color:transparent}
h1,h2,h3,h4{margin:0;line-height:1.35}
p{margin:0}
a{color:var(--blue)}
button{font-family:inherit}
.shell{max-width:1080px;margin:0 auto;padding:0 18px}
.muted{color:var(--muted)}
.small{font-size:12.5px}
.mono{font-variant-numeric:tabular-nums}
.hidden{display:none!important}

/* ---------- 顶栏 ---------- */
.topbar{background:linear-gradient(125deg,#12265c 0%,#2a53cc 58%,#4a7cf7 100%);color:#fff;padding:22px 0 26px;position:relative;overflow:hidden}
.topbar::before{content:"";position:absolute;width:420px;height:420px;right:-120px;top:-240px;border-radius:50%;background:radial-gradient(circle,rgba(255,255,255,.18),transparent 65%)}
.topbar::after{content:"";position:absolute;width:300px;height:300px;left:-140px;bottom:-220px;border-radius:50%;background:radial-gradient(circle,rgba(255,255,255,.1),transparent 65%)}
.brand{display:flex;align-items:center;gap:14px;position:relative;z-index:1;flex-wrap:wrap}
.logo{width:46px;height:46px;border-radius:14px;background:rgba(255,255,255,.16);border:1px solid rgba(255,255,255,.28);display:grid;place-items:center;font-size:24px;font-weight:800;flex:0 0 auto}
.brand h1{font-size:22px;letter-spacing:.3px}
.tagline{font-size:13px;color:#cfdcff;margin-top:3px}
.top-right{margin-left:auto;display:flex;align-items:center;gap:10px;position:relative;z-index:1}
.mode-badge{display:inline-flex;align-items:center;gap:6px;font-size:12.5px;font-weight:650;padding:6px 12px;border-radius:999px;background:rgba(255,255,255,.15);border:1px solid rgba(255,255,255,.28);color:#fff}
.mode-badge .dot{width:7px;height:7px;border-radius:50%;background:#7ff0b8}
.mode-badge.local .dot{background:#ffd479}

/* ---------- 标签栏 ---------- */
.tabbar{position:sticky;top:0;z-index:30;background:rgba(244,246,251,.92);backdrop-filter:blur(12px);border-bottom:1px solid rgba(228,233,243,.9)}
.tabbar .shell{display:flex;gap:6px;padding-top:10px;padding-bottom:10px;overflow-x:auto}
.tab{border:0;background:transparent;color:#4a5875;font-weight:650;font-size:14px;padding:9px 16px;border-radius:999px;cursor:pointer;white-space:nowrap}
.tab:hover{background:#e9eefb;color:#22345c}
.tab.active{background:#244fc6;color:#fff;box-shadow:0 6px 16px rgba(36,79,198,.28)}

main{padding:22px 0 70px}

/* ---------- 通用组件 ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:1px solid transparent;border-radius:12px;padding:10px 16px;font-size:14.5px;font-weight:650;cursor:pointer;background:var(--blue);color:#fff;transition:background .15s,box-shadow .15s,transform .05s;min-height:42px;text-decoration:none}
.btn:hover{background:var(--blue-d)}
.btn:active{transform:translateY(1px)}
.btn:disabled{opacity:.5;cursor:not-allowed}
.btn.ghost{background:#edf1fa;color:#2b3a5c}
.btn.ghost:hover{background:#e1e8f7}
.btn.outline{background:#fff;border-color:var(--line);color:#33415f}
.btn.outline:hover{background:#f7f9fe;border-color:#c8d4ec}
.btn.danger{background:#fff;border-color:#f2d2d6;color:var(--red)}
.btn.danger:hover{background:#fff5f6}
.btn.sm{padding:6px 11px;font-size:12.5px;border-radius:9px;min-height:32px}
.btn.block{width:100%}
.btn.lg{min-height:50px;font-size:16px;border-radius:14px}

.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.card + .card{margin-top:16px}
.card.flush{padding:0;overflow:hidden}
.page-head{display:flex;align-items:flex-end;justify-content:space-between;gap:16px;margin-bottom:16px;flex-wrap:wrap}
.page-head h2{font-size:22px}
.page-head .sub{color:var(--muted);font-size:13.5px;margin-top:5px;max-width:640px}
.head-actions{display:flex;gap:8px;flex-wrap:wrap}
.section-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:22px 0 12px;flex-wrap:wrap}
.section-head h3{font-size:17px}
.back{border:0;background:none;color:#475b85;font-weight:650;cursor:pointer;padding:4px 2px;font-size:14px;display:inline-flex;align-items:center;gap:5px}
.back:hover{color:var(--blue)}

.lbl{display:block;font-size:13px;font-weight:700;color:#44546f;margin:16px 0 7px}
.lbl:first-child{margin-top:0}
.input,select.input,textarea.input{width:100%;border:1.5px solid #d9e1ef;border-radius:12px;padding:11px 13px;background:#fff;color:var(--ink);font:inherit;font-size:14.5px;transition:border-color .15s,box-shadow .15s}
textarea.input{min-height:84px;resize:vertical;line-height:1.6}
.input:focus,select.input:focus,textarea.input:focus{outline:none;border-color:#7b9bf8;box-shadow:0 0 0 3px rgba(59,108,246,.13)}
.hint{font-size:12.5px;color:var(--muted);margin-top:6px;line-height:1.6}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.badge{display:inline-flex;align-items:center;gap:4px;border-radius:999px;padding:3px 9px;font-size:11.5px;font-weight:700;background:var(--blue-l);color:#3358b8;white-space:nowrap}
.badge.gray{background:#f0f3f9;color:#5d6b86}
.badge.ok{background:var(--green-l);color:var(--green)}
.badge.bad{background:var(--red-l);color:var(--red)}
.badge.warn{background:var(--amber-l);color:var(--amber)}
.badge.type{background:#f3effe;color:#6d45c9}

/* ---------- 练习列表 ---------- */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.pcard{background:#fff;border:1px solid var(--line);border-radius:16px;padding:18px;box-shadow:var(--shadow);display:flex;flex-direction:column;gap:12px;position:relative;overflow:hidden}
.pcard::before{content:"";position:absolute;left:0;top:0;bottom:0;width:4px;background:linear-gradient(180deg,#3b6cf6,#7ba2ff)}
.pcard h3{font-size:17px;padding-left:6px}
.pcard .pdesc{color:var(--muted);font-size:13px;line-height:1.6;padding-left:6px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;min-height:21px}
.pmeta{display:flex;gap:8px;flex-wrap:wrap;padding-left:6px}
.pcard .actions{display:flex;gap:7px;flex-wrap:wrap;padding-left:6px;margin-top:auto;padding-top:4px}

/* ---------- 空状态 ---------- */
.empty{padding:56px 20px;text-align:center;color:var(--muted)}
.empty .icon{width:64px;height:64px;border-radius:20px;background:var(--blue-l);display:grid;place-items:center;margin:0 auto 16px;font-size:30px;color:#4a72e8}
.empty h3{font-size:18px;color:var(--ink);margin-bottom:7px}
.empty p{font-size:14px;margin-bottom:18px}

/* ---------- 编辑练习 ---------- */
.edit-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px;flex-wrap:wrap}
.qlist{display:flex;flex-direction:column;gap:10px}
.qitem{display:flex;gap:14px;align-items:flex-start;background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px}
.qitem .order{width:32px;height:32px;border-radius:10px;background:var(--blue-l);color:#3158bd;display:grid;place-items:center;font-weight:800;font-size:14px;flex:0 0 auto}
.qitem-main{flex:1;min-width:0}
.qitem .badges{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:6px}
.stem-sm{font-size:14.5px;font-weight:600;line-height:1.65;white-space:pre-wrap;overflow-wrap:anywhere}
.qitem .ansline{font-size:12.5px;color:var(--muted);margin-top:5px;overflow-wrap:anywhere}
.qitem-actions{display:flex;gap:5px;flex-wrap:wrap;justify-content:flex-end;flex:0 0 auto;max-width:230px}
.savebar{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:20px;padding:16px 18px;background:#fff;border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);position:sticky;bottom:14px}
.savebar .muted{font-size:12.5px}

/* ---------- 弹窗 ---------- */
.overlay{position:fixed;inset:0;background:rgba(17,28,55,.46);backdrop-filter:blur(3px);z-index:100;display:flex;align-items:flex-start;justify-content:center;padding:24px 14px;overflow-y:auto}
.modal-card{background:#fff;border-radius:20px;width:100%;max-width:660px;box-shadow:0 24px 70px rgba(15,30,70,.28);padding:24px;margin:auto;animation:pop .18s ease-out}
@keyframes pop{from{transform:translateY(10px) scale(.99);opacity:0}to{transform:none;opacity:1}}
.modal-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:6px}
.modal-head h3{font-size:19px}
.icon-btn{border:0;background:#f1f4fb;width:34px;height:34px;border-radius:10px;cursor:pointer;color:#52617d;font-size:17px;display:grid;place-items:center}
.icon-btn:hover{background:#e6ebf7}
.modal-actions{display:flex;gap:9px;justify-content:flex-end;margin-top:22px;flex-wrap:wrap}
.fieldset{border:1px solid var(--line);border-radius:14px;padding:14px 16px 18px;margin-top:18px}
.fieldset legend{font-size:13px;font-weight:700;color:#44546f;padding:0 6px}
.choice-grid{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin-top:4px}
.checks{display:flex;gap:8px;flex-wrap:wrap;margin-top:4px}
.check{display:inline-flex;align-items:center;gap:7px;border:1.5px solid var(--line);border-radius:10px;padding:9px 14px;font-weight:650;cursor:pointer;background:#fff}
.check input{accent-color:var(--blue);width:17px;height:17px}
.check.on{border-color:#7b9bf8;background:var(--blue-l)}
.switch{display:flex;align-items:center;gap:9px;font-size:13.5px;font-weight:650;color:#44546f;cursor:pointer;user-select:none;margin-top:18px}
.switch input{width:18px;height:18px;accent-color:var(--blue)}

/* ---------- 二维码 ---------- */
.qr-card{max-width:430px;text-align:center}
.qr-box{width:240px;height:240px;margin:18px auto;border:1px solid var(--line);border-radius:16px;padding:8px;background:#fff}
.qr-box svg,.qr-box img{width:100%;height:100%;display:block}
.qr-title{font-size:16px;font-weight:700;margin-top:2px}
.url-box{display:flex;gap:7px;margin-top:14px}
.url-box input{flex:1;min-width:0;font-size:12.5px;color:#45536e;background:#f7f9fd}
.qr-help{font-size:12.5px;color:var(--muted);margin-top:14px;line-height:1.7;text-align:left;background:#f7f9fd;border-radius:12px;padding:11px 13px}
.qr-help b{color:#33415f}

/* ---------- 统计 ---------- */
.stat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px}
.stat{background:#f7f9fe;border:1px solid #e9eefb;border-radius:14px;padding:15px 16px}
.stat b{display:block;font-size:26px;line-height:1.2;font-variant-numeric:tabular-nums}
.stat span{font-size:12.5px;color:var(--muted)}
.stat.accent{background:var(--blue-l);border-color:#dbe5ff}
.stat.accent b{color:#2b53c8}
.stats-tool{display:flex;gap:9px;align-items:center;flex-wrap:wrap}
.stats-tool select{max-width:280px;width:280px;flex:0 1 280px}
.stats-toolbar{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:12px 14px;margin-bottom:16px;box-shadow:var(--shadow)}
.stats-toolbar select{max-width:360px;width:auto;flex:1 1 260px}
.qstat{border:1px solid var(--line);border-radius:14px;padding:16px 18px;margin-top:12px;background:#fff}
.qstat-head{display:flex;align-items:center;gap:9px;flex-wrap:wrap;margin-bottom:8px}
.qstat-head .rate{margin-left:auto;font-weight:750;font-variant-numeric:tabular-nums;font-size:13.5px}
.bars{margin-top:12px;display:flex;flex-direction:column;gap:7px}
.bar-row{display:grid;grid-template-columns:52px 1fr 86px;gap:10px;align-items:center;font-size:12.5px}
.bar-track{height:9px;border-radius:99px;background:#eef2fa;overflow:hidden}
.bar-fill{height:100%;border-radius:99px;background:#9fb6ea;min-width:2px;transition:width .3s}
.bar-row.correct .bar-fill{background:#4fc194}
.bar-row.correct .bar-key{color:var(--green);font-weight:800}
.bar-key{font-weight:700;color:#5a687f}
.bar-val{text-align:right;color:var(--muted);font-variant-numeric:tabular-nums}
.wrong-list{display:flex;gap:6px;flex-wrap:wrap;margin-top:11px}
.wrong-chip{background:#fdf1f1;border:1px solid #f6dcdc;color:#9b3a3a;border-radius:9px;padding:5px 9px;font-size:12.5px}
.essay-list{margin-top:12px;display:flex;flex-direction:column;gap:9px}
.essay-item{border:1px solid var(--line);border-radius:12px;padding:12px 14px;background:#fbfcff}
.essay-item .who{display:flex;align-items:center;gap:8px;flex-wrap:wrap;font-size:13px}
.essay-item .txt{font-size:13.5px;margin-top:7px;white-space:pre-wrap;overflow-wrap:anywhere;color:#33415f}
.essay-item .grade{display:flex;gap:6px;margin-left:auto}
.subrow{border:1px solid var(--line);border-radius:13px;background:#fff;margin-top:9px;overflow:hidden}
.subrow summary{list-style:none;display:grid;grid-template-columns:1.3fr 1fr .8fr .9fr 1fr auto;gap:10px;align-items:center;padding:13px 16px;cursor:pointer;font-size:13.5px}
.subrow summary::-webkit-details-marker{display:none}
.subrow summary:hover{background:#f8fafe}
.subrow[open] summary{background:#f7f9fe;border-bottom:1px solid var(--line)}
.subrow .sname{font-weight:700}
.subrow .sscore{font-weight:750;font-variant-numeric:tabular-nums}
.subrow .sdel{border:0;background:none;color:#b46a72;font-size:12.5px;cursor:pointer;font-weight:650}
.subdetail{padding:14px 16px;display:flex;flex-direction:column;gap:9px;background:#fbfcff}
.sd-row{font-size:13px;display:grid;grid-template-columns:1fr auto;gap:10px;padding-bottom:8px;border-bottom:1px dashed #e8edf7}
.sd-row:last-child{border-bottom:0;padding-bottom:0}
.sd-row .q{color:#3a4763;font-weight:600;overflow-wrap:anywhere}
.sd-row .a{color:var(--muted);font-size:12.5px;margin-top:3px;overflow-wrap:anywhere}
.sd-flag{font-weight:750;font-size:12.5px;white-space:nowrap}
.sd-flag.ok{color:var(--green)}.sd-flag.bad{color:var(--red)}.sd-flag.warn{color:var(--amber)}.sd-flag.gray{color:var(--muted)}
.sub-tools{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-top:18px;flex-wrap:wrap}
.stat.warn-stat{background:var(--amber-l);border-color:#f6e3b8}
.stat.warn-stat b{color:var(--amber)}
.sid-inline{font-weight:600;font-size:11.5px;color:#7a879f;background:#f0f3f9;border-radius:6px;padding:1px 6px;margin-left:6px;font-variant-numeric:tabular-nums;white-space:nowrap}
.old-badge{margin-left:6px}
.process{margin-top:15px;border-top:1px dashed #e3e9f5;padding-top:12px}
.process summary{list-style:none;cursor:pointer;display:flex;align-items:center;flex-wrap:wrap;gap:8px;font-weight:750;font-size:13.5px;color:#33415f;padding:2px 0}
.process summary::-webkit-details-marker{display:none}
.process summary::before{content:"▸";color:#7a879f;font-size:11px;line-height:1;transition:transform .15s}
.process[open] summary::before{transform:rotate(90deg)}
.process-table-wrap{margin-top:10px;overflow-x:auto;border:1px solid var(--line);border-radius:11px}
.process-table{width:100%;border-collapse:collapse;font-size:13px;min-width:400px}
.process-table th{background:#f7f9fe;color:var(--muted);font-size:11.5px;text-align:left;padding:8px 12px;border-bottom:1px solid var(--line);white-space:nowrap}
.process-table td{padding:9px 12px;border-bottom:1px solid #eef2f9;vertical-align:middle}
.process-table tbody tr:last-child td{border-bottom:0}
.process-table th:not(:first-child),.process-table td:not(:first-child){text-align:center;width:74px}
.process-name{display:flex;align-items:center;flex-wrap:wrap;font-size:13px;color:#2b3a5c}
.process-name b{font-weight:700}
.process-badge{display:inline-flex;margin-top:4px;font-size:10.5px;padding:2px 7px}
.process-summary-badge{font-size:10.5px;padding:2px 8px}
.process-legend{margin:-2px 0 4px}
.mark{display:inline-grid;place-items:center;width:25px;height:25px;border-radius:50%;font-weight:800;font-size:14px;line-height:1;vertical-align:middle}
.mark.ok{background:var(--green-l);color:var(--green)}
.mark.bad{background:var(--red-l);color:var(--red)}
.mark.none{background:#f3f5f9;color:#9aa5ba;font-size:11px;width:auto;min-width:25px;padding:0 5px;border-radius:7px}
.mark.wait{background:var(--amber-l);color:var(--amber);font-size:10.5px;width:auto;padding:0 6px;border-radius:7px}
.roster-missing{margin-top:12px}
.missing-list{display:flex;flex-wrap:wrap;gap:8px;margin-top:8px}
.missing-chip{display:inline-flex;align-items:center;gap:4px;background:#fff7e8;border:1px solid #f2dfb6;color:#7a5200;border-radius:999px;padding:7px 12px;font-size:12.5px;line-height:1.4}
.missing-chip b{color:#5c3d00}

/* ---------- 学生名单 ---------- */
.roster-summary{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:14px}
.roster-toolbar{display:flex;align-items:center;gap:10px;flex-wrap:wrap;padding:14px 16px;border-bottom:1px solid var(--line)}
.roster-toolbar .input{max-width:340px;flex:1 1 220px}
.roster-table-wrap{overflow-x:auto}
.roster-table{width:100%;border-collapse:collapse;font-size:13.5px;min-width:520px}
.roster-table th{background:#f7f9fe;color:var(--muted);font-size:12px;text-align:left;padding:10px 16px;border-bottom:1px solid var(--line);white-space:nowrap}
.roster-table td{padding:12px 16px;border-bottom:1px solid #eef2f9;vertical-align:middle}
.roster-table tbody tr:last-child td{border-bottom:0}
.roster-table tbody tr:hover{background:#fbfcff}
.roster-table .roster-sid{font-weight:750;font-variant-numeric:tabular-nums;color:#2b3a5c;white-space:nowrap}
.roster-table .row-actions{text-align:right;white-space:nowrap}
.import-warn{background:var(--amber-l);border:1px solid #f6e3b8;color:#7a5200;border-radius:11px;padding:10px 13px;font-size:12.5px;line-height:1.7;margin-top:12px}
.import-preview{max-height:280px;overflow:auto;border:1px solid var(--line);border-radius:12px;margin-top:14px}
.import-preview .roster-table{min-width:420px}
.import-preview .roster-table th{position:sticky;top:0;z-index:1}

/* ---------- 使用说明 ---------- */
.guide{font-size:14.5px;line-height:1.85;color:#2c3850}
.guide h3{font-size:17px;margin:26px 0 10px;padding-left:11px;border-left:4px solid var(--blue);line-height:1.3}
.guide h3:first-child{margin-top:0}
.guide ol,.guide ul{padding-left:22px;margin:8px 0}
.guide li{margin:5px 0}
.guide code{background:#eef2fa;border-radius:6px;padding:2px 6px;font-size:12.5px;color:#3358b8}
.guide .note{background:var(--amber-l);border:1px solid #f6e3b8;color:#7a5200;border-radius:12px;padding:13px 16px;font-size:13.5px;line-height:1.7;margin-top:18px}
.guide .info{background:var(--blue-l);border:1px solid #dbe5ff;color:#2f4c8f;border-radius:12px;padding:13px 16px;font-size:13.5px;line-height:1.7;margin-top:14px}

/* ---------- 学生端 ---------- */
body.student-mode{background:#f3f6fc}
.student-shell{max-width:720px;margin:0 auto;padding:16px 16px 130px}
.s-top{display:flex;align-items:center;gap:10px;margin-bottom:14px;flex-wrap:wrap}
.s-top .s-title{font-weight:750;font-size:15px;color:#2b3a5c}
.s-top .badge{margin-left:auto}
.s-head{background:linear-gradient(125deg,#1a3a95,#3f6ff0);border-radius:18px;padding:20px 22px;color:#fff;margin-bottom:16px;box-shadow:0 10px 30px rgba(35,70,180,.22)}
.s-head h2{font-size:21px}
.s-head p{font-size:13.5px;color:#d7e2ff;margin-top:6px;line-height:1.65;white-space:pre-wrap}
.s-head .meta{display:flex;gap:8px;margin-top:12px;font-size:12.5px;color:#eaf0ff;flex-wrap:wrap}
.s-head .meta span{background:rgba(255,255,255,.15);border:1px solid rgba(255,255,255,.22);border-radius:999px;padding:4px 10px}
.progress-wrap{margin:4px 0 16px}
.progress-info{display:flex;justify-content:space-between;font-size:12.5px;color:var(--muted);margin-bottom:7px;font-weight:650}
.progress{height:8px;background:#e5ebf8;border-radius:99px;overflow:hidden}
.progress > i{display:block;height:100%;background:linear-gradient(90deg,#3b6cf6,#6f96ff);border-radius:99px;transition:width .3s}
.qcard{background:#fff;border:1px solid var(--line);border-radius:18px;padding:22px;box-shadow:var(--shadow);animation:fadeUp .22s ease-out}
@keyframes fadeUp{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
.qcard .qmeta{display:flex;gap:7px;align-items:center;flex-wrap:wrap;margin-bottom:12px}
.stem{font-size:18px;line-height:1.85;font-weight:600;white-space:pre-wrap;overflow-wrap:anywhere}
.stem mjx-container{font-size:110%!important}
.opt{display:flex;align-items:flex-start;gap:13px;border:1.5px solid var(--line);border-radius:14px;padding:14px 16px;margin:11px 0;cursor:pointer;background:#fff;transition:border-color .15s,background .15s,box-shadow .15s;min-height:56px}
.opt:hover{border-color:#b9c9f7;background:#fbfcff}
.opt.selected{border-color:#5b82f0;background:var(--blue-l);box-shadow:0 0 0 3px rgba(59,108,246,.09)}
.opt input{width:19px;height:19px;margin:2px 0 0;accent-color:var(--blue);flex:0 0 auto}
.opt .opt-text{font-size:16px;line-height:1.65;overflow-wrap:anywhere}
.opt.correct{border-color:#41b98d;background:var(--green-l)}
.opt.correct::after{content:"✓";color:var(--green);font-weight:800;margin-left:auto}
.opt.wrong{border-color:#e28d95;background:#fff6f6}
.opt.wrong::after{content:"✕";color:var(--red);font-weight:800;margin-left:auto}
.opt input:disabled{cursor:not-allowed}
.blank-input{font-size:17px;padding:14px 15px;border-radius:13px;margin-top:14px}
.essay-input{font-size:15.5px;min-height:150px;padding:14px 15px;border-radius:13px;margin-top:14px;line-height:1.75}
.feedback{border-radius:13px;padding:13px 16px;margin:16px 0 0;line-height:1.7;font-size:14.5px;border:1px solid transparent}
.feedback.good{background:var(--green-l);border-color:#c9ecdd;color:#0d6b4b}
.feedback.bad{background:var(--red-l);border-color:#f6d7da;color:#a3303a}
.feedback.note{background:var(--amber-l);border-color:#f5e2b5;color:#7b5300}
.feedback .fb-title{font-weight:800;margin-bottom:3px;font-size:15px}
.feedback .exp{margin-top:7px;font-size:14px;line-height:1.75}
.feedback .answer{margin-top:5px;font-weight:650}
.variant{border:1px dashed #cfd9ef;background:#f9fbff;border-radius:15px;padding:16px;margin-top:16px}
.variant .vtag{font-size:12.5px;font-weight:750;color:#566a94;margin-bottom:8px;display:flex;align-items:center;gap:6px}
.variant .stem{font-size:16px}
.variant .opt{padding:11px 14px;margin:8px 0;background:#fff}
.variant .opt .opt-text{font-size:15px}
.actionbar{position:fixed;left:0;right:0;bottom:0;background:rgba(255,255,255,.94);backdrop-filter:blur(12px);border-top:1px solid var(--line);padding:12px 16px calc(12px + env(safe-area-inset-bottom));z-index:50}
.actionbar .inner{max-width:720px;margin:0 auto;display:flex;gap:10px}
.actionbar .btn{flex:1}
.timer{font-size:12.5px;color:var(--muted);font-variant-numeric:tabular-nums}
.done-card{text-align:center;padding:38px 24px}
.done-icon{width:76px;height:76px;border-radius:50%;background:var(--green-l);color:var(--green);display:grid;place-items:center;font-size:38px;margin:0 auto 18px}
.done-card h2{font-size:23px}
.done-card .who{color:var(--muted);font-size:13.5px;margin-top:6px}
.done-card .stat-grid{margin-top:24px;text-align:left}
.done-card .status{font-size:13.5px;color:var(--muted);margin-top:20px}
.done-card .status.ok{color:var(--green)}
.done-card .status.bad{color:var(--red)}
.done-actions{display:flex;gap:10px;justify-content:center;margin-top:22px;flex-wrap:wrap}
.join-rules{background:#f7f9fe;border:1px solid #e9eefb;border-radius:14px;padding:14px 16px;margin-top:18px;font-size:13px;color:#4a5875;line-height:1.8}
.join-rules b{color:#2b3a5c}
.join-roster-note{display:flex;align-items:center;gap:9px;background:var(--green-l);border:1px solid #c9ecdd;color:#0d6b4b;border-radius:12px;padding:11px 13px;font-size:13px;line-height:1.6;margin-bottom:18px;flex-wrap:wrap}
.join-roster-note.preview-note{background:var(--amber-l);border-color:#f6e3b8;color:#7a5200}
.identity-input{font-size:18px;font-weight:650;letter-spacing:.3px}
.identity-status{display:none;font-size:13px;margin-top:9px;padding:10px 12px;border-radius:10px;line-height:1.6;overflow-wrap:anywhere}
.identity-status.ok{display:block;background:var(--green-l);color:#0d6b4b;border:1px solid #c9ecdd}
.identity-status.bad{display:block;background:var(--red-l);color:#a3303a;border:1px solid #f6d7da}
.identity-status.warn{display:block;background:var(--amber-l);color:#7a5200;border:1px solid #f6e3b8}
.loading{text-align:center;padding:60px 20px;color:var(--muted);font-size:14px}
.spinner{width:34px;height:34px;border:3px solid #dfe7f7;border-top-color:var(--blue);border-radius:50%;margin:0 auto 14px;animation:spin .8s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

/* ---------- 提示 ---------- */
.toast{position:fixed;left:50%;bottom:34px;transform:translate(-50%,20px);background:#1d2b4c;color:#fff;padding:11px 18px;border-radius:12px;font-size:13.5px;font-weight:600;box-shadow:0 10px 30px rgba(15,28,60,.3);opacity:0;pointer-events:none;transition:.22s;z-index:200;max-width:calc(100vw - 40px);text-align:center}
.toast.show{opacity:1;transform:translate(-50%,0)}

@media(max-width:720px){
  .shell{padding:0 14px}
  .topbar{padding:18px 0 20px}
  .brand h1{font-size:19px}
  .tagline{font-size:12px}
  .top-right{width:100%;margin-left:0;margin-top:12px}
  main{padding:18px 0 60px}
  .card{padding:17px}
  .row2,.choice-grid{grid-template-columns:1fr}
  .grid{grid-template-columns:1fr}
  .qitem{flex-wrap:wrap}
  .qitem-actions{max-width:none;width:100%;justify-content:flex-start;padding-left:46px}
  .savebar{position:static}
  .stats-tool{width:100%}
  .stats-tool select{max-width:none;width:auto;flex:1}
  .stats-toolbar select{flex:1 1 100%;max-width:none}
  .subrow summary{grid-template-columns:1fr auto auto;grid-auto-rows:auto;gap:4px 8px}
  .subrow summary .hide-m{display:none}
  .subrow .sscore{justify-self:end}
  .stem{font-size:17px}
  .qcard{padding:18px}
  .actionbar{padding:10px 14px calc(10px + env(safe-area-inset-bottom))}
  .modal-card{padding:18px;border-radius:16px}
  .overlay{padding:12px 10px}
  .bar-row{grid-template-columns:44px 1fr 74px;gap:8px}
  .process-table{min-width:0;font-size:12.5px}
  .process-table th,.process-table td{padding:8px 7px}
  .process-table th:not(:first-child),.process-table td:not(:first-child){width:44px}
  .process-badge{font-size:10px;padding:2px 6px}
  .student-shell{padding:12px 14px 120px}
  .roster-toolbar{padding:12px 14px}
  .roster-toolbar .input{max-width:none;flex:1 1 100%}
  .roster-table{min-width:0;font-size:12.5px}
  .roster-table th,.roster-table td{padding-left:8px;padding-right:8px}
  .roster-table .btn.sm{padding:5px 8px;font-size:12px}
  .identity-input{font-size:17px}
  .join-roster-note{font-size:12.5px}
  .stat-grid{grid-template-columns:repeat(auto-fit,minmax(135px,1fr))}
  .stat.wide-mobile{grid-column:1/-1}
}

/* ---------- 老师端登录 ---------- */
.login-shell{min-height:100vh;display:grid;place-items:center;padding:24px 18px;background:linear-gradient(160deg,#eef3ff 0%,#f7f9ff 45%,#eaf7f2 100%)}
.login-card{width:100%;max-width:420px;padding:32px 28px}
.login-logo{width:56px;height:56px;border-radius:18px;display:grid;place-items:center;font-size:28px;font-weight:800;color:#fff;background:linear-gradient(135deg,#2a53cc,#4a7cf7);box-shadow:0 10px 24px rgba(42,83,204,.25);margin-bottom:18px}
.login-card h2{font-size:22px}
.login-card .sub{color:var(--muted);font-size:13.5px;margin-top:8px}
.login-error{min-height:20px;color:var(--red);font-size:13px;font-weight:600;margin:10px 0 4px}

/* ---------- Word 导入预览 ---------- */
.modal-card.wide{max-width:760px}
.word-preview{max-height:46vh;overflow:auto;display:flex;flex-direction:column;gap:8px;margin:12px 0;padding-right:2px}
.word-q{border:1px solid var(--line);border-radius:12px;padding:9px 12px;font-size:13.5px;background:#fbfcff}
.word-q.skip{opacity:.55;background:#f6f7fa}
.word-q-head{display:flex;gap:8px;align-items:center;margin-bottom:4px;flex-wrap:wrap}
.word-stem{white-space:pre-wrap}
.word-opt{margin-left:14px;color:#3d4a68}
.word-ans{margin-top:5px;color:var(--green);font-weight:600}
.word-exp{margin-top:2px;color:var(--muted);font-size:12.5px}
.word-warn{background:var(--amber-l);border:1px solid #ffe1a8;color:var(--amber);border-radius:10px;padding:7px 12px;font-size:12.5px;margin:10px 0;display:flex;flex-direction:column;gap:2px}

/* ---------- 二维码降级（组件不可用时展示可复制链接） ---------- */
.qr-fallback{padding:8px 2px;text-align:left}
.qr-fallback p{color:var(--muted);font-size:13.5px;margin-bottom:10px;line-height:1.6}
.qr-fallback .input{width:100%;font-size:13px;word-break:break-all}