:root{
  --bg:#f4f6fb; --panel:#ffffff; --panel-2:#f8f9fd; --line:#e4e8f2; --ink:#141a2e; --ink-2:#4a5470; --muted:#7a839c;
  --pri:#4f46e5; --pri-2:#7c3aed; --pri-soft:#eef0ff; --acc:#06b6d4;
  --good:#059669; --good-soft:#e7f8f1; --warn:#d97706; --warn-soft:#fff5e5; --bad:#e11d48; --bad-soft:#ffecf0; --info:#2563eb; --info-soft:#e9f1ff;
  --side:#111633; --side-ink:#c9cfee; --side-on:#ffffff;
  --r:14px; --r-sm:10px; --sh:0 1px 2px rgba(20,26,46,.05),0 6px 20px rgba(20,26,46,.06);
  --grad:linear-gradient(135deg,#4f46e5 0%,#7c3aed 55%,#c026d3 100%);
}
:root[data-theme="dark"]{
  --bg:#0c1022; --panel:#151a33; --panel-2:#1a2040; --line:#262d52; --ink:#eef0fb; --ink-2:#bfc5e3; --muted:#8d95ba;
  --pri-soft:#22275a; --good-soft:#0f3328; --warn-soft:#3a2a10; --bad-soft:#3b1522; --info-soft:#13254a; --side:#090c1c;
  --sh:0 1px 2px rgba(0,0,0,.3),0 8px 24px rgba(0,0,0,.25);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0c1022; --panel:#151a33; --panel-2:#1a2040; --line:#262d52; --ink:#eef0fb; --ink-2:#bfc5e3; --muted:#8d95ba;
    --pri-soft:#22275a; --good-soft:#0f3328; --warn-soft:#3a2a10; --bad-soft:#3b1522; --info-soft:#13254a; --side:#090c1c;
    --sh:0 1px 2px rgba(0,0,0,.3),0 8px 24px rgba(0,0,0,.25);
  }
}
*{box-sizing:border-box}
html,body{margin:0}
body{font-family:"Be Vietnam Pro",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--ink);font-size:15px;line-height:1.55;-webkit-font-smoothing:antialiased}
a{color:var(--pri);text-decoration:none} a:hover{text-decoration:underline}
h1,h2,h3,h4{line-height:1.25;margin:0 0 .5em;letter-spacing:-.01em}
h1{font-size:1.6rem;font-weight:800} h2{font-size:1.25rem;font-weight:700} h3{font-size:1.05rem;font-weight:700}
p{margin:.3em 0 .8em}
.muted{color:var(--muted)} .small{font-size:.85rem} .center{text-align:center} .right{text-align:right} .nowrap{white-space:nowrap}
hr{border:0;border-top:1px solid var(--line);margin:16px 0}

/* ===== Khung ===== */
.shell{display:flex;min-height:100vh}
.side{width:258px;flex-shrink:0;background:var(--side);color:var(--side-ink);display:flex;flex-direction:column;position:sticky;top:0;height:100vh;overflow-y:auto;padding:18px 12px}
.brand{display:flex;align-items:center;gap:10px;color:#fff;font-size:1rem;line-height:1.15;padding:4px 8px 16px}
.brand:hover{text-decoration:none}
.brand-ico{width:40px;height:40px;border-radius:12px;background:var(--grad);display:grid;place-items:center;font-size:20px;box-shadow:0 6px 18px rgba(124,58,237,.45)}
.brand.big{color:var(--ink);font-size:1.25rem;margin-bottom:10px}
.side-user{display:flex;gap:10px;align-items:center;background:rgba(255,255,255,.06);border-radius:12px;padding:10px;margin:0 4px 10px}
.side-user b{color:#fff;display:block;font-size:.9rem;line-height:1.2} .side-user small{color:var(--side-ink);font-size:.78rem}
.side nav{flex:1}
.nav-grp{font-size:.7rem;text-transform:uppercase;letter-spacing:.08em;color:#7f88b8;margin:14px 10px 6px;font-weight:700}
.side nav a{display:flex;align-items:center;gap:10px;padding:8px 10px;border-radius:10px;color:var(--side-ink);font-size:.92rem;margin:1px 0}
.side nav a:hover{background:rgba(255,255,255,.07);text-decoration:none;color:#fff}
.side nav a.on{background:var(--grad);color:var(--side-on);font-weight:600;box-shadow:0 6px 16px rgba(79,70,229,.35)}
.ni{width:22px;text-align:center}
.side-foot{border-top:1px solid rgba(255,255,255,.08);padding-top:10px;margin-top:10px;display:flex;justify-content:space-between}
.side-foot a{color:var(--side-ink);font-size:.85rem;padding:6px 8px}
.main{flex:1;min-width:0;display:flex;flex-direction:column}
.top{display:flex;align-items:center;gap:12px;padding:12px 28px;background:var(--panel);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.crumb{flex:1;color:var(--muted);font-size:.9rem} .crumb b{color:var(--ink)}
.top-r{display:flex;align-items:center;gap:10px}
.hamb{display:none;border:0;background:none;font-size:22px;cursor:pointer;color:var(--ink)}
.icon-btn{border:1px solid var(--line);background:var(--panel);border-radius:10px;width:36px;height:36px;cursor:pointer;color:var(--ink)}
.ai-badge{font-size:.78rem;padding:5px 10px;border-radius:999px;background:var(--warn-soft);color:var(--warn);font-weight:600}
.ai-badge.live{background:var(--good-soft);color:var(--good)}
.content{padding:24px 28px 60px;max-width:1360px;width:100%}
.page-head{display:flex;justify-content:space-between;align-items:flex-end;gap:16px;margin-bottom:20px;flex-wrap:wrap}
.page-head h1{margin:0}
.page-head p{margin:.25em 0 0}
.ph-act{display:flex;gap:8px;flex-wrap:wrap}

/* ===== Thành phần ===== */
.card{background:var(--panel);border:1px solid var(--line);border-radius:var(--r);padding:20px;box-shadow:var(--sh);margin-bottom:18px}
.card.pad0{padding:0;overflow:hidden}
.card-h{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:12px;flex-wrap:wrap}
.card-h h3{margin:0}
.grid2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}
.grid3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
.grid4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px}
.split{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(0,1fr);gap:18px}
.row{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.row.between{justify-content:space-between}
.stack>*+*{margin-top:10px}

.hero{background:var(--grad);color:#fff;border-radius:18px;padding:24px 26px;margin-bottom:20px;position:relative;overflow:hidden;box-shadow:0 12px 30px rgba(79,70,229,.3)}
.hero::after{content:"";position:absolute;right:-60px;top:-60px;width:240px;height:240px;border-radius:50%;background:rgba(255,255,255,.12)}
.hero::before{content:"";position:absolute;right:120px;bottom:-90px;width:180px;height:180px;border-radius:50%;background:rgba(255,255,255,.08)}
.hero h1{color:#fff;margin:2px 0 6px}
.hero p{opacity:.9;margin:0;max-width:640px}
.hero small{text-transform:uppercase;letter-spacing:.08em;opacity:.8;font-weight:600;font-size:.72rem}
.hero .btn{position:relative;z-index:1}

.kpi{display:flex;gap:14px;align-items:center;background:var(--panel);border:1px solid var(--line);border-radius:var(--r);padding:16px;box-shadow:var(--sh)}
.kpi-ico{width:46px;height:46px;border-radius:12px;background:var(--pri-soft);display:grid;place-items:center;font-size:22px;flex-shrink:0}
.kpi.good .kpi-ico{background:var(--good-soft)} .kpi.warn .kpi-ico{background:var(--warn-soft)} .kpi.bad .kpi-ico{background:var(--bad-soft)} .kpi.info .kpi-ico{background:var(--info-soft)}
.kpi-v{font-size:1.5rem;font-weight:800;line-height:1.1}
.kpi-l{color:var(--muted);font-size:.85rem}
.kpi-h{font-size:.78rem;color:var(--ink-2)}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:9px 16px;border-radius:10px;border:1px solid var(--line);background:var(--panel);color:var(--ink);font:inherit;font-weight:600;font-size:.9rem;cursor:pointer;transition:.15s;text-decoration:none;white-space:nowrap}
.btn:hover{border-color:var(--pri);color:var(--pri);text-decoration:none}
.btn.primary{background:var(--grad);border:0;color:#fff;box-shadow:0 4px 14px rgba(79,70,229,.3)}
.btn.primary:hover{filter:brightness(1.08);color:#fff}
.btn.soft{background:var(--pri-soft);border-color:transparent;color:var(--pri)}
.btn.danger{color:var(--bad)} .btn.danger:hover{border-color:var(--bad)}
.btn.good{background:var(--good);border-color:var(--good);color:#fff}
.btn.sm{padding:5px 10px;font-size:.8rem;border-radius:8px}
.btn.lg{padding:13px 22px;font-size:1rem}
.btn.block{width:100%}
.btn:disabled{opacity:.55;cursor:not-allowed}
.btn.loading{pointer-events:none;opacity:.75}
.btn.loading::before{content:"";width:14px;height:14px;border:2px solid currentColor;border-right-color:transparent;border-radius:50%;animation:spin .7s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

label{display:block;font-weight:600;font-size:.86rem;color:var(--ink-2);margin-bottom:12px}
input,select,textarea{display:block;width:100%;margin-top:5px;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--panel);color:var(--ink);font:inherit;font-weight:400;font-size:.95rem;transition:.15s}
input:focus,select:focus,textarea:focus{outline:none;border-color:var(--pri);box-shadow:0 0 0 3px rgba(79,70,229,.15)}
textarea{min-height:90px;resize:vertical}
input[type=checkbox],input[type=radio]{width:auto;display:inline-block;margin:0 6px 0 0;accent-color:var(--pri)}
label.check{display:flex;align-items:center;font-weight:500}
.inline-form{display:flex;gap:8px;align-items:flex-end;flex-wrap:wrap}
.inline-form label{margin:0}
.inline-form input,.inline-form select{min-width:140px}
fieldset{border:1px dashed var(--line);border-radius:12px;padding:14px;margin:0 0 14px}
legend{font-weight:700;padding:0 6px;font-size:.9rem}

.chip{display:inline-block;padding:2px 10px;border-radius:999px;font-size:.78rem;font-weight:600;background:var(--panel-2);color:var(--ink-2);border:1px solid var(--line);white-space:nowrap}
.chip.good{background:var(--good-soft);color:var(--good);border-color:transparent}
.chip.warn{background:var(--warn-soft);color:var(--warn);border-color:transparent}
.chip.bad{background:var(--bad-soft);color:var(--bad);border-color:transparent}
.chip.info{background:var(--info-soft);color:var(--info);border-color:transparent}
.chip.pri{background:var(--pri-soft);color:var(--pri);border-color:transparent}
.chip.ai{background:linear-gradient(135deg,#ede9fe,#fae8ff);color:#7c3aed;border-color:transparent}
:root[data-theme="dark"] .chip.ai{background:#2d1f55;color:#c4b5fd}

.avatar{width:36px;height:36px;border-radius:50%;display:inline-grid;place-items:center;font-weight:700;font-size:.9rem;flex-shrink:0;background:hsl(var(--h) 80% 92%);color:hsl(var(--h) 60% 35%)}
.avatar.lg{width:64px;height:64px;font-size:1.4rem}

table.tbl{width:100%;border-collapse:collapse;font-size:.9rem}
.tbl th{text-align:left;font-size:.75rem;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);font-weight:700;padding:10px 12px;border-bottom:1px solid var(--line);background:var(--panel-2)}
.tbl td{padding:10px 12px;border-bottom:1px solid var(--line);vertical-align:middle}
.tbl tr:last-child td{border-bottom:0}
.tbl tr:hover td{background:var(--panel-2)}
.tbl-wrap{overflow-x:auto}
.who{display:flex;align-items:center;gap:10px}
.who b{display:block;line-height:1.2} .who small{color:var(--muted)}

.flash{padding:12px 16px;border-radius:12px;margin-bottom:14px;font-weight:500;background:var(--good-soft);color:var(--good)}
.flash.bad{background:var(--bad-soft);color:var(--bad)} .flash.warn{background:var(--warn-soft);color:var(--warn)} .flash.info{background:var(--info-soft);color:var(--info)}

.bar{height:8px;border-radius:99px;background:var(--panel-2);overflow:hidden;border:1px solid var(--line)}
.bar i{display:block;height:100%;background:var(--grad);border-radius:99px}
.bar.good i{background:var(--good)} .bar.warn i{background:var(--warn)} .bar.bad i{background:var(--bad)}

.empty{text-align:center;padding:40px 20px}
.empty-ico{font-size:44px;margin-bottom:6px}

.list-item{display:flex;align-items:center;gap:12px;padding:12px 0;border-bottom:1px solid var(--line)}
.list-item:last-child{border-bottom:0}
.li-ico{width:40px;height:40px;border-radius:12px;background:var(--pri-soft);display:grid;place-items:center;font-size:19px;flex-shrink:0}
.li-main{flex:1;min-width:0}
.li-main b{display:block}
.li-main small{color:var(--muted)}

.tabs{display:flex;gap:4px;border-bottom:1px solid var(--line);margin-bottom:18px;overflow-x:auto}
.tabs a{padding:10px 14px;color:var(--muted);font-weight:600;border-bottom:2px solid transparent;white-space:nowrap}
.tabs a.on{color:var(--pri);border-bottom-color:var(--pri)}
.tabs a:hover{text-decoration:none;color:var(--ink)}

.tile-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:12px}
.tile{border:1px solid var(--line);border-radius:12px;padding:14px;background:var(--panel);cursor:pointer;transition:.15s;display:block;color:var(--ink)}
.tile:hover{border-color:var(--pri);transform:translateY(-1px);box-shadow:var(--sh);text-decoration:none}
.tile .t-ico{font-size:24px} .tile b{display:block;margin-top:6px} .tile small{color:var(--muted)}
.tile.on{border-color:var(--pri);background:var(--pri-soft)}

/* ===== Câu hỏi / làm bài ===== */
.q{border:1px solid var(--line);border-radius:14px;padding:18px;margin-bottom:14px;background:var(--panel)}
.q-h{display:flex;gap:8px;align-items:center;margin-bottom:10px;flex-wrap:wrap}
.q-no{width:30px;height:30px;border-radius:9px;background:var(--grad);color:#fff;display:grid;place-items:center;font-weight:700;font-size:.85rem}
.q-body{font-size:1rem;white-space:pre-wrap;margin-bottom:12px}
.opt{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border:1px solid var(--line);border-radius:10px;margin-bottom:8px;cursor:pointer;font-weight:400;color:var(--ink);transition:.12s}
.opt:hover{border-color:var(--pri)}
.opt input{margin-top:4px}
.opt.sel{border-color:var(--pri);background:var(--pri-soft)}
.opt.right{border-color:var(--good);background:var(--good-soft)}
.opt.wrong{border-color:var(--bad);background:var(--bad-soft)}
.opt .ol{font-weight:700;color:var(--pri);min-width:18px}
.tf4 td{padding:8px}
.tf4-btn{display:inline-flex;gap:6px}
.tf4-btn label{margin:0;display:inline-flex;align-items:center;gap:4px;border:1px solid var(--line);border-radius:8px;padding:4px 10px;cursor:pointer;font-weight:600}
.explain{background:var(--panel-2);border-left:3px solid var(--pri);border-radius:8px;padding:10px 12px;font-size:.92rem;margin-top:10px}
.quiz-bar{position:sticky;top:61px;z-index:10;background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:10px 16px;display:flex;align-items:center;gap:14px;margin-bottom:16px;box-shadow:var(--sh)}
.timer{font-variant-numeric:tabular-nums;font-weight:800;font-size:1.15rem;color:var(--pri)}
.timer.low{color:var(--bad)}
.qnav{display:flex;flex-wrap:wrap;gap:5px}
.qnav a{width:28px;height:28px;border-radius:7px;border:1px solid var(--line);display:grid;place-items:center;font-size:.75rem;color:var(--ink-2);font-weight:600}
.qnav a.done{background:var(--pri);color:#fff;border-color:var(--pri)}

.ai-box{border:1px solid #ddd6fe;background:linear-gradient(135deg,rgba(237,233,254,.6),rgba(250,232,255,.5));border-radius:14px;padding:16px 18px;margin-bottom:16px}
:root[data-theme="dark"] .ai-box{border-color:#3b2f6b;background:linear-gradient(135deg,#1d1840,#251a3d)}
.ai-box h3{display:flex;align-items:center;gap:8px}
.ai-box ul{margin:.3em 0 .6em;padding-left:1.2em}
.err-row{border-left:3px solid var(--bad);padding:6px 10px;margin:6px 0;background:var(--panel);border-radius:6px;font-size:.92rem}
.err-row s{color:var(--bad)} .err-row ins{color:var(--good);text-decoration:none;font-weight:600}

/* ===== Điểm danh ===== */
.att-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(170px,1fr));gap:10px}
.att{border:2px solid var(--good);background:var(--good-soft);border-radius:12px;padding:10px;cursor:pointer;user-select:none;display:flex;gap:8px;align-items:center;transition:.1s}
.att b{font-size:.88rem;line-height:1.2;display:block}
.att small{font-weight:700;font-size:.72rem}
.att[data-s="A"]{border-color:var(--bad);background:var(--bad-soft)} .att[data-s="A"] small{color:var(--bad)}
.att[data-s="E"]{border-color:var(--info);background:var(--info-soft)} .att[data-s="E"] small{color:var(--info)}
.att[data-s="L"]{border-color:var(--warn);background:var(--warn-soft)} .att[data-s="L"] small{color:var(--warn)}
.att[data-s="P"] small{color:var(--good)}

/* ===== Thi đua ===== */
.merit-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:10px}
.merit-card{border:1px solid var(--line);border-radius:12px;padding:12px;text-align:center;cursor:pointer;background:var(--panel);transition:.12s}
.merit-card:hover,.merit-card.sel{border-color:var(--pri);background:var(--pri-soft)}
.merit-card .pts{font-weight:800;font-size:1.1rem}
.reason-chips{display:flex;flex-wrap:wrap;gap:6px}
.reason-chips button{border:1px solid var(--line);background:var(--panel);border-radius:999px;padding:6px 12px;cursor:pointer;font:inherit;font-size:.85rem;color:var(--ink)}
.reason-chips button.pos{border-color:var(--good);color:var(--good)} .reason-chips button.neg{border-color:var(--bad);color:var(--bad)}
.podium{display:flex;align-items:flex-end;gap:10px;justify-content:center;margin:10px 0}
.podium div{flex:1;max-width:140px;text-align:center;border-radius:12px 12px 0 0;padding:10px;color:#fff;font-weight:700}

/* ===== Công cụ lớp học ===== */
.wheel-wrap{position:relative;width:min(420px,90vw);margin:0 auto}
.wheel-wrap canvas{width:100%;height:auto;display:block}
.wheel-pin{position:absolute;top:-6px;left:50%;transform:translateX(-50%);width:0;height:0;border-left:16px solid transparent;border-right:16px solid transparent;border-top:28px solid var(--bad);filter:drop-shadow(0 2px 3px rgba(0,0,0,.3));z-index:2}
.big-name{font-size:clamp(2rem,6vw,3.6rem);font-weight:800;text-align:center;background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent;min-height:1.3em}
.big-timer{font-size:clamp(3.5rem,14vw,8rem);font-weight:800;text-align:center;font-variant-numeric:tabular-nums;line-height:1}
.team{border:1px solid var(--line);border-radius:12px;padding:12px}
.team h4{margin:0 0 8px}

/* ===== Chat gia sư ===== */
.chat{display:flex;flex-direction:column;gap:10px;max-height:60vh;overflow-y:auto;padding:4px}
.msg{max-width:80%;padding:10px 14px;border-radius:14px;white-space:pre-wrap}
.msg.user{align-self:flex-end;background:var(--grad);color:#fff;border-bottom-right-radius:4px}
.msg.assistant{align-self:flex-start;background:var(--panel-2);border:1px solid var(--line);border-bottom-left-radius:4px}

/* ===== Biểu đồ ===== */
.spark{width:100%;height:120px}
.legend{display:flex;gap:12px;flex-wrap:wrap;font-size:.8rem;color:var(--muted)}
.legend i{display:inline-block;width:10px;height:10px;border-radius:3px;margin-right:4px;vertical-align:middle}
.hbar{display:grid;grid-template-columns:150px 1fr 48px;gap:10px;align-items:center;margin:6px 0;font-size:.88rem}

/* ===== Đăng nhập ===== */
.auth{display:grid;grid-template-columns:1.1fr 1fr;min-height:100vh}
.auth.single{display:grid;place-items:center;grid-template-columns:1fr;padding:30px 16px}
.auth-art{background:var(--grad);color:#fff;display:grid;place-items:center;padding:40px;position:relative;overflow:hidden}
.auth-art::after{content:"";position:absolute;width:420px;height:420px;border-radius:50%;background:rgba(255,255,255,.08);right:-120px;bottom:-140px}
.auth-art-in{max-width:480px;position:relative;z-index:1}
.auth-art .brand{color:#fff}
.auth-art h2{font-size:1.9rem;font-weight:800;line-height:1.25}
.auth-art em{font-style:normal;color:#fde68a}
.auth-feat{list-style:none;padding:0;margin:20px 0 0}
.auth-feat li{display:flex;gap:12px;align-items:center;margin:12px 0;font-size:1rem;opacity:.95}
.auth-feat span{width:36px;height:36px;border-radius:10px;background:rgba(255,255,255,.16);display:grid;place-items:center;flex-shrink:0}
.auth-form{display:grid;place-items:center;padding:30px 16px}
.auth-card{width:100%;max-width:400px;padding:30px}
.auth-card.wide{max-width:620px}

.print-only{display:none}
.badge-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(130px,1fr));gap:12px}
.badge{border:1px solid var(--line);border-radius:14px;padding:14px;text-align:center;background:var(--panel)}
.badge .b-ico{font-size:34px}
.badge.locked{opacity:.38;filter:grayscale(1)}
.badge b{display:block;font-size:.85rem;margin-top:4px}
.badge small{color:var(--muted);font-size:.75rem}

.login-card{border:1px dashed var(--ink-2);border-radius:10px;padding:12px;break-inside:avoid;font-size:.9rem}
.login-cards{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}

@media (max-width:1100px){.grid4{grid-template-columns:repeat(2,minmax(0,1fr))}.split{grid-template-columns:1fr}}
@media (max-width:860px){
  .side{position:fixed;left:-280px;z-index:50;transition:left .2s;box-shadow:0 0 40px rgba(0,0,0,.4)}
  .side.open{left:0}
  .hamb{display:block}
  .top{padding:10px 16px}
  .content{padding:18px 16px 50px}
  .grid2,.grid3{grid-template-columns:1fr}
  .auth{grid-template-columns:1fr}.auth-art{display:none}
  .hbar{grid-template-columns:100px 1fr 40px}
  .login-cards{grid-template-columns:1fr 1fr}
  .crumb{font-size:.8rem}
}
@media (max-width:520px){.grid4{grid-template-columns:1fr 1fr}.kpi{padding:12px}.kpi-v{font-size:1.2rem}.ai-badge{display:none}}
@media print{
  .side,.top,.no-print,.flash{display:none!important}
  .content{padding:0;max-width:none}
  .card{box-shadow:none;border:0;padding:0}
  body{background:#fff;color:#000;font-size:12.5pt}
  .print-only{display:block}
  .q{break-inside:avoid;border:0;padding:6px 0;margin:0}
  .login-cards{grid-template-columns:repeat(3,1fr)}
}

/* ===== Học liệu: nhúng, trình chiếu, video, sách lật ===== */
.embed-16x9{position:relative;width:100%;aspect-ratio:16/9;background:#000;border-radius:12px;overflow:hidden;margin:10px 0}
.embed-16x9 iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.embed-guard .guard-pop{position:absolute;top:0;right:0;width:72px;height:60px;z-index:3;background:transparent;cursor:not-allowed}
.slides-stage{position:relative;width:100%;aspect-ratio:16/9;background:#111;border-radius:14px;overflow:hidden;box-shadow:var(--sh)}
.slides-stage iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.slides-stage .guard-pop{position:absolute;top:0;right:0;width:80px;height:64px;z-index:3}
.slides-stage:fullscreen{border-radius:0}
.vplayer{position:relative;background:#000;border-radius:14px;overflow:hidden;box-shadow:var(--sh);user-select:none}
.vplayer .vp-frame{position:relative;width:100%;aspect-ratio:16/9}
.vplayer .vp-frame iframe,.vplayer .vp-frame>div{position:absolute;inset:0;width:100%;height:100%;border:0}
.vplayer .vp-shield{position:absolute;inset:0;z-index:2;cursor:pointer}
.vplayer .vp-big{position:absolute;inset:0;display:grid;place-items:center;z-index:3;pointer-events:none;font-size:64px;color:#fff;text-shadow:0 4px 20px rgba(0,0,0,.6);transition:opacity .2s}
.vp-bar{display:flex;align-items:center;gap:8px;flex-wrap:wrap;padding:10px 12px;background:#0b0e1f;color:#fff}
.vp-bar button,.vp-bar select{background:rgba(255,255,255,.1);color:#fff;border:1px solid rgba(255,255,255,.15);border-radius:8px;padding:6px 10px;font:inherit;font-size:.85rem;cursor:pointer;width:auto;margin:0}
.vp-bar button:hover{background:rgba(255,255,255,.2)}
.vp-bar select option{color:#000}
.vp-time{font-variant-numeric:tabular-nums;font-size:.85rem;opacity:.9;min-width:96px;text-align:center}
.vp-seek{flex:1;min-width:140px;accent-color:#a78bfa;margin:0;padding:0;height:6px;background:none;border:0}
.vplayer:fullscreen{border-radius:0;display:flex;flex-direction:column;justify-content:center}
.vplayer:fullscreen .vp-frame{aspect-ratio:auto;flex:1}
.book-wrap{background:radial-gradient(ellipse at center,#2a2f55 0%,#141833 70%);border-radius:16px;padding:22px 14px;user-select:none;-webkit-user-select:none}
.book-wrap:fullscreen{border-radius:0;display:flex;flex-direction:column;justify-content:center}
.book{position:relative;margin:0 auto;perspective:2600px;display:flex;justify-content:center}
.book .leaf{position:relative;background:#fff;overflow:hidden;box-shadow:0 10px 30px rgba(0,0,0,.45)}
.book .leaf.l{border-radius:6px 0 0 6px}.book .leaf.r{border-radius:0 6px 6px 0}
.book .leaf.l::after{content:"";position:absolute;inset:0 0 0 auto;width:40px;background:linear-gradient(to left,rgba(0,0,0,.22),transparent)}
.book .leaf.r::after{content:"";position:absolute;inset:0 auto 0 0;width:40px;background:linear-gradient(to right,rgba(0,0,0,.22),transparent)}
.book .leaf.empty{background:transparent;box-shadow:none}
.book .leaf.empty::after{display:none}
.book canvas,.book img{display:block;width:100%;height:100%}
.book .turn{position:absolute;top:0;transform-style:preserve-3d;transition:transform .7s cubic-bezier(.45,.05,.3,1);z-index:5}
.book .turn .face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;background:#fff;overflow:hidden}
.book .turn .face.back{transform:rotateY(180deg)}
.book-bar{display:flex;justify-content:center;align-items:center;gap:10px;margin-top:16px;flex-wrap:wrap;color:#fff}
.book-bar button{background:rgba(255,255,255,.12);color:#fff;border:1px solid rgba(255,255,255,.2);border-radius:10px;padding:8px 14px;cursor:pointer;font:inherit}
.book-bar button:disabled{opacity:.35;cursor:default}
.book-bar input{width:64px;margin:0;padding:6px;text-align:center;background:rgba(255,255,255,.1);color:#fff;border:1px solid rgba(255,255,255,.2)}
.book-loading{color:#c7cbe8;text-align:center;padding:60px 0}
.mat-card .mat-ico{width:48px;height:48px;border-radius:14px;display:grid;place-items:center;font-size:24px;background:var(--pri-soft);flex-shrink:0}