:root{--ink:#17233b;--muted:#6e7789;--line:#e3e8f1;--blue:#365edb;--blue2:#6e8ff0;--green:#187253;--red:#b43e49;--amber:#9a6815;--bg:#f4f6fa;--paper:#fff}
*{box-sizing:border-box}body{margin:0;min-height:100vh;color:var(--ink);background:var(--bg);font-family:"Microsoft YaHei UI","PingFang SC",system-ui,sans-serif}button,input,select{font:inherit}button{cursor:pointer}a{color:inherit;text-decoration:none}.hidden{display:none!important}
.platform-shell{min-height:100vh}.platform-bar{display:flex;align-items:center;gap:24px;min-height:72px;padding:0 4vw;border-bottom:1px solid var(--line);background:#fff}.platform-brand{display:flex;align-items:center;gap:10px;margin-right:auto;font-weight:800}.platform-brand span{display:grid;width:36px;height:36px;place-items:center;border-radius:11px;color:#fff;background:linear-gradient(145deg,#2447ae,#6889eb)}.platform-nav{display:flex;gap:8px}.platform-nav a{padding:9px 12px;border-radius:9px;color:var(--muted);font-size:13px}.platform-nav a.active{color:var(--blue);background:#eef2ff;font-weight:700}.user-pill{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:13px}.user-pill strong{color:var(--ink)}.ghost,.primary,.danger{border:0;border-radius:10px;padding:10px 14px;font-weight:700}.ghost{color:var(--ink);background:#edf0f6}.primary{color:#fff;background:var(--blue)}.danger{color:#fff;background:var(--red)}
.platform-main{width:min(1220px,92vw);margin:0 auto;padding:36px 0 70px}.page-head{display:flex;align-items:end;justify-content:space-between;gap:24px;margin-bottom:26px}.eyebrow{margin:0 0 8px;color:var(--blue);font-size:11px;font-weight:800;letter-spacing:2px}.page-head h1{margin:0;font-size:34px}.page-head p{margin:8px 0 0;color:var(--muted)}.head-actions{display:flex;gap:10px}
.metric-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-bottom:20px}.metric{padding:20px;border:1px solid var(--line);border-radius:18px;background:#fff}.metric span{display:block;color:var(--muted);font-size:12px}.metric strong{display:block;margin-top:8px;font-size:30px}.metric.live strong{color:var(--green)}
.panel{padding:22px;border:1px solid var(--line);border-radius:20px;background:#fff;box-shadow:0 12px 35px rgba(29,46,82,.05)}.panel-head{display:flex;align-items:center;justify-content:space-between;gap:18px;margin-bottom:18px}.panel-head h2{margin:0;font-size:20px}.panel-head p{margin:5px 0 0;color:var(--muted);font-size:12px}.split{display:grid;grid-template-columns:1.2fr .8fr;gap:18px}.stack{display:grid;gap:18px}
.account-search{position:relative;display:block;width:min(270px,45%)}.account-search span{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.account-search input{width:100%;padding:10px 13px 10px 38px;border:1px solid var(--line);border-radius:10px;color:var(--ink);background:#f8f9fc;outline:none}.account-search:before{content:"⌕";position:absolute;left:13px;top:7px;color:#7e899d;font-size:20px}.account-search input:focus{border-color:#8ca5ec;background:#fff;box-shadow:0 0 0 3px #edf2ff}
.form-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.form-grid label,.field{display:grid;gap:6px;color:var(--muted);font-size:12px}.form-grid input,.form-grid select,.field input,.field select{width:100%;padding:11px 12px;border:1px solid var(--line);border-radius:10px;color:var(--ink);background:#fff;outline:none}.form-grid input:focus,.form-grid select:focus,.field input:focus{border-color:#8ca5ec;box-shadow:0 0 0 3px #edf2ff}.form-actions{grid-column:1/-1;display:flex;justify-content:flex-end;gap:10px}.message{min-height:20px;margin:12px 0 0;color:var(--red);font-size:12px}.message.ok{color:var(--green)}
.table-wrap{overflow:auto}table{width:100%;border-collapse:collapse;font-size:13px}th,td{padding:13px 10px;border-bottom:1px solid #eef0f5;text-align:left;white-space:nowrap}th{color:var(--muted);font-size:11px}.role,.status{display:inline-flex;padding:4px 8px;border-radius:99px;font-size:11px}.role.admin{color:#6842aa;background:#f1eafd}.role.teacher{color:#2457ac;background:#eaf1ff}.role.student{color:#237050;background:#e8f7f0}.status.online{color:var(--green);background:#e8f7f0}.status.offline{color:var(--muted);background:#eef0f4}.status.alert{color:var(--red);background:#ffedef}.mini{border:0;border-radius:8px;padding:7px 9px;background:#edf1f8;font-size:11px}.mini.warn{color:var(--red);background:#ffedef}
.student-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.student-card{display:grid;gap:14px;padding:19px;border:1px solid var(--line);border-radius:18px;background:#fff}.student-card.alert{border-color:#efbdc2;box-shadow:0 10px 28px rgba(180,62,73,.08)}.student-top{display:flex;align-items:start;justify-content:space-between;gap:15px}.student-top h3{margin:0}.student-top p{margin:5px 0 0;color:var(--muted);font-size:12px}.state-line{display:grid;grid-template-columns:1fr 1fr;gap:8px}.state-line div{padding:10px;border-radius:11px;background:#f6f8fb}.state-line span,.state-line strong{display:block}.state-line span{color:var(--muted);font-size:10px}.state-line strong{margin-top:4px;font-size:12px;overflow:hidden;text-overflow:ellipsis}.teacher-copy{min-height:48px;margin:0;color:#4f5b70;font-size:12px;line-height:1.65}.card-actions{display:flex;gap:9px}.card-actions button{flex:1}.takeover-active{padding:10px;border-radius:10px;color:#8b4e0c;background:#fff2d9;font-size:12px}.empty{padding:36px;text-align:center;color:var(--muted)}
.login-page{display:grid;min-height:100vh;grid-template-columns:1.05fr .95fr;background:#fff}.login-art{position:relative;display:grid;align-content:center;padding:8vw;color:#fff;background:linear-gradient(145deg,#172b69,#365edb 60%,#7895ef);overflow:hidden}.login-art:after{content:"";position:absolute;width:520px;height:520px;right:-170px;bottom:-230px;border:1px solid rgba(255,255,255,.3);border-radius:50%;box-shadow:0 0 0 70px rgba(255,255,255,.05),0 0 0 140px rgba(255,255,255,.04)}.login-art p{max-width:520px;color:#dce5ff;line-height:1.8}.login-art h1{margin:10px 0;font-size:clamp(42px,5vw,72px);line-height:1.1}.login-card-wrap{display:grid;place-items:center;padding:40px}.login-card{width:min(420px,100%)}.login-card h2{margin:0;font-size:30px}.login-card>p{margin:10px 0 26px;color:var(--muted)}.login-card form{display:grid;gap:15px}.login-card .primary{padding:13px}.demo-box{margin-top:24px;padding:14px;border-radius:12px;color:var(--muted);background:#f5f7fb;font-size:11px;line-height:1.7}.login-logo{display:flex;align-items:center;gap:10px;margin-bottom:45px;font-weight:800}.login-logo span{display:grid;width:38px;height:38px;place-items:center;border-radius:12px;color:var(--blue);background:#eef2ff}
@media(max-width:950px){.metric-grid{grid-template-columns:repeat(2,1fr)}.split{grid-template-columns:1fr}.student-grid{grid-template-columns:1fr 1fr}.login-page{grid-template-columns:1fr}.login-art{display:none}.platform-nav{display:none}}
@media(max-width:620px){.platform-bar{padding:0 16px}.platform-main{width:94vw;padding-top:24px}.user-pill span{display:none}.page-head{display:block}.head-actions{margin-top:15px}.metric-grid,.student-grid,.form-grid{grid-template-columns:1fr}.metric-grid{grid-template-columns:1fr 1fr}.form-actions{grid-column:auto}.login-card-wrap{padding:25px}.panel-head{align-items:stretch;flex-direction:column}.account-search{width:100%}}
.context-dialog{width:min(620px,calc(100vw - 32px));border:0;border-radius:22px;padding:0;box-shadow:0 28px 80px rgba(15,23,42,.25)}
.context-dialog::backdrop{background:rgba(15,23,42,.48);backdrop-filter:blur(3px)}
.context-dialog form{display:grid;grid-template-columns:1fr 1fr;gap:16px;padding:26px}
.context-dialog .dialog-head,.context-dialog .dialog-actions,.context-dialog .form-note,.context-dialog label:has(textarea){grid-column:1/-1}
.context-dialog .dialog-head{display:flex;justify-content:space-between;align-items:flex-start}.context-dialog .dialog-head h2{margin:3px 0}.context-dialog .dialog-head p{margin:0;color:var(--muted)}
.context-dialog label{display:grid;gap:7px;font-size:13px;font-weight:700;color:#334155}.context-dialog input,.context-dialog select,.context-dialog textarea{width:100%;box-sizing:border-box;border:1px solid var(--line);border-radius:11px;padding:11px 12px;background:#fff;font:inherit;color:#0f172a}.context-dialog textarea{resize:vertical;min-height:130px}
.context-dialog .form-note{margin:0;color:var(--muted);font-size:13px}.context-dialog .dialog-actions{display:flex;justify-content:flex-end;gap:10px}
@media(max-width:620px){.context-dialog form{grid-template-columns:1fr}.context-dialog label{grid-column:1/-1}}