:root{
  --brand:#0EA5E9; --brand-deep:#0369A1; --brand-ink:#FFFFFF; --brand-soft:#E0F2FE;
  --ground:#F3F8FB; --paper:#FFFFFF; --ink:#0F2533; --muted:#5B7080; --line:#DCE7EE; --soft:#EEF5F9;
  --lv1:#10B981; --lv2:#3B82F6; --lv3:#F59E0B;
  --ok:#059669; --ok-soft:#D1FAE5; --warn:#B45309; --warn-soft:#FEF3C7; --bad:#E11D48; --bad-soft:#FFE4E6;
  --mm-root:#0EA5E9; --mm-root-ink:#FFFFFF;
  --mm1:#10B981; --mm1-ink:#FFFFFF; --mm2:#3B82F6; --mm2-ink:#FFFFFF; --mm3:#F59E0B; --mm3-ink:#3A2600;
  --mm4:#F43F5E; --mm4-ink:#FFFFFF; --mm5:#8B5CF6; --mm5-ink:#FFFFFF; --mm6:#06B6D4; --mm6-ink:#06303A;
  --shadow:0 1px 2px rgba(15,37,51,.06),0 8px 24px -12px rgba(15,37,51,.18);
  --r:12px;
  --font:"Be Vietnam Pro",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    color-scheme:dark;
    --brand:#38BDF8; --brand-deep:#7DD3FC; --brand-ink:#04202E; --brand-soft:#0C3347;
    --ground:#0D1820; --paper:#13222C; --ink:#E4EEF4; --muted:#93A8B6; --line:#24394A; --soft:#172C3A;
    --lv1:#34D399; --lv2:#60A5FA; --lv3:#FBBF24;
    --ok:#34D399; --ok-soft:#0F3A2C; --warn:#FBBF24; --warn-soft:#3A2E0A; --bad:#FB7185; --bad-soft:#3F1621;
    --mm-root:#38BDF8; --mm-root-ink:#04202E;
    --mm1:#34D399; --mm1-ink:#062A1E; --mm2:#60A5FA; --mm2-ink:#081E3D; --mm3:#FBBF24; --mm3-ink:#3A2600;
    --mm4:#FB7185; --mm4-ink:#3D0812; --mm5:#A78BFA; --mm5-ink:#1E1040; --mm6:#22D3EE; --mm6-ink:#06303A;
    --shadow:0 1px 2px rgba(0,0,0,.3),0 8px 24px -12px rgba(0,0,0,.6);
  }
}
:root[data-theme="dark"]{
  color-scheme:dark;
  --brand:#38BDF8; --brand-deep:#7DD3FC; --brand-ink:#04202E; --brand-soft:#0C3347;
  --ground:#0D1820; --paper:#13222C; --ink:#E4EEF4; --muted:#93A8B6; --line:#24394A; --soft:#172C3A;
  --lv1:#34D399; --lv2:#60A5FA; --lv3:#FBBF24;
  --ok:#34D399; --ok-soft:#0F3A2C; --warn:#FBBF24; --warn-soft:#3A2E0A; --bad:#FB7185; --bad-soft:#3F1621;
  --mm-root:#38BDF8; --mm-root-ink:#04202E;
  --mm1:#34D399; --mm1-ink:#062A1E; --mm2:#60A5FA; --mm2-ink:#081E3D; --mm3:#FBBF24; --mm3-ink:#3A2600;
  --mm4:#FB7185; --mm4-ink:#3D0812; --mm5:#A78BFA; --mm5-ink:#1E1040; --mm6:#22D3EE; --mm6-ink:#06303A;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 8px 24px -12px rgba(0,0,0,.6);
}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--ground);color:var(--ink);font-family:var(--font);font-size:15px;line-height:1.6}
a{color:var(--brand-deep);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3{line-height:1.25;text-wrap:balance;margin:0}
button,input,select,textarea{font:inherit;color:inherit}
:focus-visible{outline:2px solid var(--brand);outline-offset:2px}
.wrap{max-width:1160px;margin:0 auto;padding-inline:20px}
.num{font-variant-numeric:tabular-nums}
.muted{color:var(--muted)}
.small{font-size:13px}
.stack{display:flex;flex-direction:column;gap:16px}
.row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.sp{flex:1}

/* ---------- demo banner & header ---------- */
.demo{background:var(--warn-soft);color:var(--warn);font-size:13px;padding:8px 0}
.demo .wrap{display:flex;flex-wrap:wrap;gap:6px 14px;align-items:center}
.demo b{color:var(--ink)}
.demo button{background:none;border:0;color:var(--warn);text-decoration:underline;cursor:pointer;padding:0;font-size:13px}
header.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:color-mix(in srgb,var(--paper) 92%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
header.top .wrap{display:flex;align-items:center;gap:14px;min-height:62px;flex-wrap:wrap;padding-block:8px}
.logo{display:flex;align-items:center;gap:10px;font-weight:800;font-size:18px;color:var(--ink)}
.logo:hover{text-decoration:none}
.logo i{width:34px;height:34px;border-radius:10px;background:var(--brand);display:grid;place-items:center;color:var(--brand-ink);font-style:normal}
.nav{display:flex;gap:4px;flex-wrap:wrap}
.nav a{padding:6px 10px;border-radius:8px;color:var(--muted);font-weight:600;font-size:14px}
.nav a:hover,.nav a.on{background:var(--soft);color:var(--ink);text-decoration:none}
.who{margin-left:auto;display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.chip-bal{display:inline-flex;align-items:center;gap:6px;background:var(--brand-soft);color:var(--brand-deep);font-weight:700;border-radius:999px;padding:5px 12px;font-size:14px}

/* ---------- buttons, forms ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid var(--line);background:var(--paper);border-radius:10px;padding:9px 16px;font-weight:600;font-size:14px;cursor:pointer;color:var(--ink);text-decoration:none;white-space:nowrap}
.btn:hover{border-color:var(--muted);text-decoration:none}
.btn.pri{background:var(--brand);border-color:var(--brand);color:var(--brand-ink)}
.btn.pri:hover{filter:brightness(1.05)}
.btn.ok{background:var(--ok);border-color:var(--ok);color:#fff}
.btn.ghost{background:transparent;border-color:transparent;color:var(--muted)}
.btn.bad{color:var(--bad);border-color:var(--bad-soft)}
.btn.sm{padding:6px 11px;font-size:13px;border-radius:8px}
.btn.lg{padding:12px 20px;font-size:15px}
.btn[disabled]{opacity:.55;cursor:not-allowed}
label.f{display:flex;flex-direction:column;gap:6px;font-weight:600;font-size:14px}
label.f span.h{font-weight:400;color:var(--muted);font-size:13px}
input.i,select.i,textarea.i{width:100%;border:1px solid var(--line);background:var(--paper);border-radius:10px;padding:10px 12px;font-size:15px}
textarea.i{min-height:120px;resize:vertical;line-height:1.5}
textarea.code{font-family:ui-monospace,Menlo,Consolas,monospace;font-size:13px;min-height:320px}
input.i:focus,select.i:focus,textarea.i:focus{border-color:var(--brand);outline:none;box-shadow:0 0 0 3px var(--brand-soft)}
.check{display:flex;gap:8px;align-items:center;font-weight:600;font-size:14px}
.err{background:var(--bad-soft);color:var(--bad);border-radius:10px;padding:10px 12px;font-size:14px}
.note{background:var(--soft);border-radius:10px;padding:10px 12px;font-size:14px;color:var(--muted)}

/* ---------- cards & badges ---------- */
.card{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:20px}
.badge{display:inline-flex;align-items:center;gap:4px;font-size:12px;font-weight:700;border-radius:999px;padding:3px 10px;white-space:nowrap}
.b-free{background:var(--ok-soft);color:var(--ok)}
.b-own{background:var(--brand-soft);color:var(--brand-deep)}
.b-price{background:var(--soft);color:var(--ink)}
.b-pend{background:var(--warn-soft);color:var(--warn)}
.b-bad{background:var(--bad-soft);color:var(--bad)}
.b-hide{background:var(--soft);color:var(--muted)}

/* ---------- home ---------- */
main{padding-block:28px 60px;min-height:60vh}
.hero{display:grid;grid-template-columns:1.05fr 1fr;gap:28px;align-items:center;margin-bottom:34px}
.hero h1{font-size:clamp(28px,4.2vw,44px);font-weight:800;letter-spacing:-.02em}
.hero h1 em{font-style:normal;color:var(--brand)}
.hero p.lead{font-size:17px;color:var(--muted);margin:14px 0 22px;max-width:52ch}
.hero .mini{background:var(--paper);border:1px solid var(--line);border-radius:16px;padding:10px;box-shadow:var(--shadow);overflow:hidden}
.hero .mini .mm-bar,.hero .mini .mm-hint{display:none}
.hero .mini .mm-stage{border:0;background-size:18px 18px}
.plans{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-bottom:40px}
.plan{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:16px 18px;display:flex;gap:14px;align-items:flex-start}
.plan .ic{flex:none;width:40px;height:40px;border-radius:10px;display:grid;place-items:center;font-size:20px}
.plan h3{font-size:16px}
.plan p{margin:2px 0 0;color:var(--muted);font-size:14px}
.sec-h{display:flex;align-items:baseline;gap:12px;margin:0 0 14px}
.sec-h h2{font-size:22px;font-weight:800}
.levels{display:flex;flex-direction:column;gap:28px}
.lvl h3{font-size:15px;font-weight:700;color:var(--muted);text-transform:uppercase;letter-spacing:.06em;margin-bottom:10px;display:flex;align-items:center;gap:8px}
.lvl h3 i{width:10px;height:10px;border-radius:3px;background:var(--c)}
.grades{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px}
.grade{position:relative;background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:14px 16px 16px;color:var(--ink);overflow:hidden;display:flex;flex-direction:column;gap:2px;min-height:122px}
.grade:hover{text-decoration:none;border-color:var(--c);box-shadow:var(--shadow)}
.grade::before{content:"";position:absolute;inset:0 0 auto 0;height:5px;background:var(--c)}
.grade .n{font-size:40px;font-weight:800;line-height:1;color:var(--c);margin-top:6px}
.grade .t{font-weight:700}
.grade .s{font-size:13px;color:var(--muted)}

/* ---------- grade page ---------- */
.crumb{font-size:14px;color:var(--muted);margin-bottom:10px}
.page-h{display:flex;flex-wrap:wrap;align-items:flex-end;gap:14px;margin-bottom:20px}
.page-h h1{font-size:clamp(26px,3.4vw,36px);font-weight:800}
.combo{display:flex;flex-wrap:wrap;gap:16px;align-items:center;background:linear-gradient(135deg,var(--brand-soft),var(--paper));border:1px solid var(--line);border-radius:var(--r);padding:18px 20px;margin-bottom:22px}
.combo .big{font-size:28px;font-weight:800;color:var(--brand-deep)}
.combo s{color:var(--muted)}
.subj{margin-bottom:22px}
.subj h2{font-size:18px;font-weight:700;margin-bottom:10px}
.lessons{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);overflow:hidden}
.lrow{display:flex;align-items:center;gap:14px;padding:13px 16px;border-top:1px solid var(--line);color:var(--ink)}
.lrow:first-child{border-top:0}
.lrow:hover{background:var(--soft);text-decoration:none}
.lrow .o{flex:none;width:34px;height:34px;border-radius:9px;background:var(--soft);display:grid;place-items:center;font-weight:700;color:var(--muted)}
.lrow .tt{flex:1;min-width:0}
.lrow .tt b{display:block;font-weight:600}
.lrow .tt span{display:block;font-size:13px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.empty{text-align:center;padding:40px 16px;color:var(--muted)}

/* ---------- lesson ---------- */
.lesson-h{margin-bottom:16px}
.lesson-h h1{font-size:clamp(24px,3.2vw,34px);font-weight:800;margin:6px 0 10px}
.mm-bar{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:10px}
.mm-bar button{border:1px solid var(--line);background:var(--paper);border-radius:8px;padding:6px 12px;font-weight:600;font-size:13px;cursor:pointer}
.mm-stage{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);overflow:auto;background-image:radial-gradient(var(--line) 1px,transparent 1px);background-size:22px 22px}
.mm-stage svg{display:block;margin:0 auto}
.mm-node.tog{cursor:pointer}
.mm-hint{font-size:13px;color:var(--muted);margin:8px 0 0}
.two{display:grid;grid-template-columns:1.4fr 1fr;gap:18px;margin-top:18px}
.video{position:relative;aspect-ratio:16/9;max-width:100%;background:#000;border-radius:var(--r);overflow:hidden}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.video-empty{aspect-ratio:16/9;max-width:100%;border:1px dashed var(--line);border-radius:var(--r);display:grid;place-items:center;color:var(--muted);text-align:center;padding:16px;background:var(--paper)}
.notes ul{margin:8px 0 0;padding-left:20px;display:flex;flex-direction:column;gap:6px}
.lock{text-align:center;padding:36px 20px;background:var(--paper);border:1px solid var(--line);border-radius:var(--r)}
.lock .ic{width:60px;height:60px;border-radius:50%;background:var(--brand-soft);color:var(--brand-deep);display:grid;place-items:center;margin:0 auto 12px}
.lock h2{font-size:21px;font-weight:800}
.lock p{color:var(--muted);max-width:48ch;margin:8px auto 18px}
.lock .row{justify-content:center}
.pn{display:flex;justify-content:space-between;gap:12px;margin-top:22px;flex-wrap:wrap}

/* ---------- auth ---------- */
.auth{max-width:440px;margin:10px auto}
.auth h1{font-size:26px;font-weight:800;margin-bottom:4px}
.seg{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.seg label{border:1px solid var(--line);border-radius:10px;padding:10px;text-align:center;cursor:pointer;font-weight:600;font-size:14px}
.seg input{position:absolute;opacity:0;pointer-events:none}
.seg label:has(input:checked){border-color:var(--brand);background:var(--brand-soft);color:var(--brand-deep)}

/* ---------- account / admin ---------- */
.side{display:grid;grid-template-columns:220px 1fr;gap:22px;align-items:start}
.tabs{display:flex;flex-direction:column;gap:2px;background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:8px}
.tabs a{padding:9px 12px;border-radius:8px;color:var(--muted);font-weight:600;font-size:14px;display:flex;justify-content:space-between;gap:8px}
.tabs a:hover{background:var(--soft);text-decoration:none;color:var(--ink)}
.tabs a.on{background:var(--brand-soft);color:var(--brand-deep)}
.stat{display:flex;flex-direction:column;gap:2px}
.stat .v{font-size:30px;font-weight:800}
.stat .k{font-size:13px;color:var(--muted);font-weight:600}
.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:14px}
.tbl-wrap{overflow-x:auto;background:var(--paper);border:1px solid var(--line);border-radius:var(--r)}
table.t{width:100%;border-collapse:collapse;font-size:14px}
table.t th{text-align:left;font-size:12px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);font-weight:700;padding:10px 12px;border-bottom:1px solid var(--line);white-space:nowrap}
table.t td{padding:10px 12px;border-bottom:1px solid var(--line);vertical-align:middle}
table.t tr:last-child td{border-bottom:0}
td.r,th.r{text-align:right}
.plus{color:var(--ok);font-weight:700}
.minus{color:var(--bad);font-weight:700}
.amounts{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}
.amounts button{border:1px solid var(--line);background:var(--paper);border-radius:10px;padding:12px 6px;font-weight:700;cursor:pointer}
.amounts button.on{border-color:var(--brand);background:var(--brand-soft);color:var(--brand-deep)}
.pay{display:grid;grid-template-columns:260px 1fr;gap:22px;align-items:start}
.qr{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:10px;text-align:center}
.qr img{width:100%;display:block}
.kv{display:grid;grid-template-columns:auto 1fr;gap:8px 14px;font-size:15px}
.kv dt{color:var(--muted)}
.kv dd{margin:0;font-weight:700;display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.code{font-family:ui-monospace,Menlo,Consolas,monospace;background:var(--warn-soft);color:var(--ink);padding:2px 8px;border-radius:6px;letter-spacing:.04em}
.editor{display:grid;grid-template-columns:1fr 1fr;gap:18px;align-items:start}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}

/* ---------- modal & toast ---------- */
.modal{position:fixed;inset:0;background:rgba(8,20,28,.5);display:grid;place-items:center;z-index:50;padding:16px}
.modal .box{background:var(--paper);border-radius:16px;max-width:420px;width:100%;padding:22px;box-shadow:var(--shadow)}
.modal h3{font-size:19px;font-weight:800;margin-bottom:8px}
.modal .row{justify-content:flex-end;margin-top:18px}
.toast{position:fixed;left:50%;bottom:calc(20px + env(safe-area-inset-bottom,0px));transform:translateX(-50%);background:var(--ink);color:var(--paper);padding:11px 18px;border-radius:10px;font-weight:600;font-size:14px;z-index:60;box-shadow:var(--shadow);max-width:calc(100% - 32px)}
footer{border-top:1px solid var(--line);padding-block:22px;color:var(--muted);font-size:13px}
footer .wrap{display:flex;flex-wrap:wrap;gap:8px 20px;justify-content:space-between}
.spin{display:inline-block;width:18px;height:18px;border:2px solid var(--line);border-top-color:var(--brand);border-radius:50%;animation:sp .8s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}
@media (prefers-reduced-motion:reduce){.spin{animation-duration:3s}}

@media (max-width:860px){
  .hero,.two,.side,.pay,.editor{grid-template-columns:1fr}
  .plans{grid-template-columns:1fr}
  .tabs{flex-direction:row;flex-wrap:wrap}
  .amounts{grid-template-columns:repeat(2,1fr)}
  .grid3{grid-template-columns:1fr 1fr}
  .pay .qr{max-width:280px}
}
@media (max-width:480px){
  .grid2,.grid3{grid-template-columns:1fr}
  .nav{order:3;width:100%}
  .grades{grid-template-columns:repeat(2,1fr)}
}

/* ---------- v2: lesson sections, editor, 2FA ---------- */
.sh{font-size:18px;font-weight:700;margin:0}
.ssh{font-size:15px;font-weight:700;margin:6px 0 0;color:var(--muted)}
.lsec{display:flex;flex-direction:column;gap:10px;margin-bottom:6px}
.seg2{display:inline-flex;background:var(--soft);border-radius:9px;padding:3px;gap:2px}
.seg2 button{border:0;background:transparent;padding:5px 12px;border-radius:7px;font-weight:600;font-size:13px;cursor:pointer;color:var(--muted)}
.seg2 button.on{background:var(--paper);color:var(--ink);box-shadow:var(--shadow)}
.mm-img img{display:block;max-width:100%;height:auto;margin:0 auto;border-radius:var(--r);border:1px solid var(--line);background:#fff}
.rich h3{font-size:16px;margin:14px 0 6px}
.rich h3:first-child{margin-top:0}
.rich p{margin:0 0 10px}
.rich ul{margin:0 0 10px;padding-left:20px;display:flex;flex-direction:column;gap:4px}
.upl{display:grid;grid-template-columns:260px 1fr;gap:16px;align-items:start}
.upl-pv{min-height:140px;border:1px dashed var(--line);border-radius:10px;display:grid;place-items:center;padding:8px;background:var(--ground)}
.upl-pv img{max-width:100%;max-height:220px;display:block}
.soon{opacity:.7;display:flex;flex-direction:column;gap:8px;align-items:flex-start;border-style:dashed}
.savebar{position:sticky;bottom:calc(10px + env(safe-area-inset-bottom,0px));background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:10px 12px;box-shadow:var(--shadow);z-index:5}
.otp{font-size:26px;letter-spacing:.4em;text-align:center;font-weight:700}
.steps{margin:0;padding-left:20px;display:flex;flex-direction:column;gap:10px}
@media (max-width:860px){.upl{grid-template-columns:1fr}}
.editor>*,.two>*,.side>*,.pay>*,.hero>*,.upl>*{min-width:0}
.qr-box svg{display:block;width:100%;height:auto}
.qr-cap{font-size:13px;color:#0F2533;margin-top:4px;line-height:1.4}
.paybox{max-width:560px}
.pay2{display:grid;grid-template-columns:200px 1fr;gap:16px;align-items:start}
.paystate{display:flex;gap:12px;align-items:flex-start;background:var(--soft);border-radius:10px;padding:12px;margin-top:14px}
.paystate .spin{flex:none;margin-top:3px}
.okdot{flex:none;width:26px;height:26px;border-radius:50%;background:var(--ok);color:#fff;display:grid;place-items:center;font-weight:800}
.modal .box{max-height:calc(100vh - 32px);overflow:auto}
@media (max-width:520px){.pay2{grid-template-columns:1fr}.pay2 .qr{max-width:240px;margin:0 auto}}
.paybox{max-width:620px}
.pay2{grid-template-columns:190px minmax(0,1fr)}
.pay2 .kv{grid-template-columns:auto minmax(0,1fr)}
.pay2 .kv dd{min-width:0;overflow-wrap:anywhere}
.modal .box.paybox{max-width:620px}

/* ---------- v3: mindmap cho điện thoại & máy tính ---------- */
.mm{display:flex;flex-direction:column;gap:10px}
.mm .mm-bar{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:0}
.mm .mm-bar button{border:1px solid var(--line);background:var(--paper);border-radius:8px;padding:7px 12px;font-weight:600;font-size:13px;cursor:pointer;min-height:36px}
.mm .mm-bar .seg2{padding:3px}
.mm .mm-bar .seg2 button{border:0;min-height:32px}
.mm .mm-bar .seg2 button.on{background:var(--paper)}
.mm-maptools{display:inline-flex;gap:6px;flex-wrap:wrap}
.mm-maptools button[data-a="in"],.mm-maptools button[data-a="out"],.mm-maptools button[data-a="fit"]{width:38px;padding:0;font-size:17px}
.mm-fullbtn{margin-left:auto}
.mm .mm-stage{position:relative;overflow:hidden;touch-action:none;cursor:grab;user-select:none;-webkit-user-select:none;min-height:200px}
.mm .mm-stage:active{cursor:grabbing}
.mm .mm-stage svg{position:absolute;left:0;top:0;transform-origin:0 0;margin:0;max-width:none!important;width:auto}
.mm .mm-hint{margin:0}
.mm .mm-list{display:none}
.mm.is-list .mm-list{display:block}
.mm.is-list .mm-stage,.mm.is-list .mm-maptools{display:none}
.mm-mini .mm-stage{cursor:default;touch-action:auto;border:0;background-size:18px 18px}
.mm-mini .mm-stage svg{pointer-events:none}
/* danh sách */
.ml{display:flex;flex-direction:column;gap:12px}
.ml-root{background:var(--mm-root);color:var(--mm-root-ink);font-weight:800;font-size:19px;border-radius:14px;padding:14px 18px;text-align:center;box-shadow:0 4px 0 color-mix(in srgb,var(--mm-root) 30%,transparent)}
.ml-b{border:2px solid var(--c);border-radius:14px;background:color-mix(in srgb,var(--c) 7%,var(--paper));overflow:hidden}
.ml-b summary{list-style:none;cursor:pointer}
.ml-b summary::-webkit-details-marker{display:none}
.ml-h{background:var(--c);color:var(--ci);font-weight:700;font-size:17px;padding:12px 44px 12px 16px;position:relative}
.ml-h::after,.ml-i>details>summary::after{content:"–";position:absolute;right:14px;top:50%;transform:translateY(-50%);font-weight:800;font-size:18px}
details:not([open])>.ml-h::after,.ml-i>details:not([open])>summary::after{content:"+"}
.ml ul{list-style:none;margin:0;padding:8px 12px 12px 12px;display:flex;flex-direction:column;gap:8px}
.ml ul ul{padding:8px 0 2px 14px;border-left:3px solid color-mix(in srgb,var(--c) 45%,transparent);margin-left:6px;gap:6px}
.ml-i>span,.ml-i>details>summary{display:block;position:relative;font-size:16px;line-height:1.45;padding:9px 12px;border-radius:10px;background:var(--paper);border:1px solid color-mix(in srgb,var(--c) 35%,var(--line))}
.ml-i.d2>details>summary{font-weight:700;background:color-mix(in srgb,var(--c) 18%,var(--paper));padding-right:36px}
.ml-i.d3>span,.ml-i.d3>details>summary,.ml-i.d4>span{font-size:15px}
/* toàn màn hình */
.mm.mm-full{position:fixed;inset:0;z-index:100;background:var(--paper);padding:calc(10px + env(safe-area-inset-top,0px)) 10px calc(10px + env(safe-area-inset-bottom,0px));gap:8px}
.mm.mm-full .mm-stage{flex:1;height:auto!important;border-radius:12px}
.mm.mm-full .mm-hint{display:none}
html.mm-lock,html.mm-lock body{overflow:hidden}
@media (max-width:700px){
  .mm .mm-bar{gap:6px}
  .mm-fullbtn{margin-left:0}
  .mm-maptools button[data-a="fold"],.mm-maptools button[data-a="open"]{display:none}
}
.video.vert{aspect-ratio:9/16;max-height:80vh;width:auto;margin:0 auto;height:min(80vh,calc((100vw - 40px)*16/9))}
.jump{display:none}
@media (max-width:700px){
  main{padding-block:16px 40px}
  .wrap{padding-inline:16px}
  .lesson-h h1{font-size:23px}
  .jump{display:flex;gap:6px;position:sticky;top:var(--hdrH,64px);z-index:15;background:var(--ground);padding:8px 0;margin:0 0 8px;overflow-x:auto}
  .jump button{flex:1 0 auto;border:1px solid var(--line);background:var(--paper);border-radius:999px;padding:8px 9px;font-weight:700;font-size:13.5px;white-space:nowrap}
  .two{gap:14px}
  .rich{font-size:16px}
  .pn{flex-direction:column}
  .pn .btn{white-space:normal;text-align:left;justify-content:flex-start}
  .btn.lg{width:100%;white-space:normal}
  header.top .wrap{gap:8px;min-height:56px}
  .logo{font-size:16px}
  .who .btn.sm{padding:6px 9px}
}
@media (max-width:700px){
  header.top{position:static}
  .jump{top:env(safe-area-inset-top,0px)}
}

/* v4: cỡ chữ đồng đều trong dạng danh sách */
.ml-h{font-size:16px}
.ml-i>span,.ml-i>details>summary,.ml-i.d3>span,.ml-i.d3>details>summary,.ml-i.d4>span{font-size:16px}
.ml-root{font-size:20px}

/* v5: chọn môn học, học kì */
.grid4{display:grid;grid-template-columns:repeat(4,1fr);gap:12px}
.picks{display:flex;flex-direction:column;gap:10px;margin-bottom:18px;position:sticky;top:calc(var(--hdrH,62px) - 1px);box-shadow:0 -12px 0 var(--ground);z-index:10;background:var(--ground);padding-block:8px}
.chips{display:flex;gap:8px;overflow-x:auto;padding-bottom:2px;scrollbar-width:thin}
.chips button{flex:none;border:1px solid var(--line);background:var(--paper);border-radius:999px;padding:8px 14px;font-weight:700;font-size:14px;cursor:pointer;color:var(--ink);display:inline-flex;gap:6px;align-items:center}
.chips button.on{background:var(--brand);border-color:var(--brand);color:var(--brand-ink)}
.chips .cnt{font-size:12px;font-weight:700;background:var(--soft);color:var(--muted);border-radius:999px;padding:1px 7px}
.chips button.on .cnt{background:rgba(255,255,255,.25);color:inherit}
.small-chips button{padding:5px 12px;font-size:13px}
@media (max-width:860px){.grid4{grid-template-columns:1fr 1fr}}
@media (max-width:700px){.picks{top:env(safe-area-inset-top,0px)}}

/* ===== Bài tập tự chấm ===== */
.ex-sec .sh{margin-bottom:6px}
.ex{display:flex;flex-direction:column;gap:14px}
.ex-top{display:flex;flex-wrap:wrap;gap:6px 16px;align-items:center;justify-content:space-between;font-size:15px}
.ex-best{background:var(--ok-soft);color:var(--ok);border-radius:999px;padding:4px 12px;font-size:14px}
.ex-bar{height:8px;border-radius:99px;background:var(--soft);overflow:hidden}
.ex-bar i{display:block;height:100%;background:var(--brand);border-radius:99px;transition:width .25s}
.ex-list{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:14px}
.ex-q{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:16px 18px;scroll-margin-top:120px}
.ex-q.is-ok{border-color:var(--ok);box-shadow:inset 4px 0 0 var(--ok)}
.ex-q.is-bad{border-color:var(--bad);box-shadow:inset 4px 0 0 var(--bad)}
.ex-q.is-part{border-color:var(--warn);box-shadow:inset 4px 0 0 var(--warn)}
.ex-h{display:flex;gap:8px;align-items:center;margin-bottom:6px}
.ex-n{font-weight:800}
.ex-tag{font-size:12px;font-weight:700;border-radius:999px;padding:2px 10px;background:var(--brand-soft);color:var(--brand-deep)}
.ex-tag.t-ds{background:var(--warn-soft);color:var(--warn)}
.ex-tag.t-tl{background:var(--ok-soft);color:var(--ok)}
.ex-text{font-weight:600;line-height:1.5;margin-bottom:10px}
.ex-opts{display:grid;gap:8px}
.ex-opt{display:flex;gap:10px;align-items:flex-start;border:1.5px solid var(--line);border-radius:12px;padding:10px 12px;cursor:pointer;line-height:1.45;min-height:44px}
.ex-opt:hover{border-color:var(--brand)}
.ex-opt input{position:absolute;opacity:0;pointer-events:none}
.ex-opt:has(input:checked){border-color:var(--brand);background:var(--brand-soft)}
.ex-opt:has(input:focus-visible){outline:3px solid var(--brand);outline-offset:2px}
.ex-l{flex:none;width:26px;height:26px;border-radius:50%;display:inline-grid;place-items:center;font-weight:800;font-size:13px;background:var(--soft);color:var(--ink)}
.ex-opt:has(input:checked) .ex-l{background:var(--brand);color:var(--brand-ink)}
.ex-opt.ok{border-color:var(--ok);background:var(--ok-soft)}
.ex-opt.ok .ex-l{background:var(--ok);color:#fff}
.ex-opt.bad{border-color:var(--bad);background:var(--bad-soft)}
.ex-opt.bad .ex-l{background:var(--bad);color:#fff}
.ex-ds{display:grid;gap:8px}
.ex-st{display:grid;grid-template-columns:auto 1fr auto;gap:10px;align-items:center;border:1.5px solid var(--line);border-radius:12px;padding:8px 10px;line-height:1.45}
.ex-st.ok{border-color:var(--ok);background:var(--ok-soft)}
.ex-st.bad{border-color:var(--bad);background:var(--bad-soft)}
.ex-tf{display:flex;gap:6px}
.ex-tf label{cursor:pointer}
.ex-tf input{position:absolute;opacity:0;pointer-events:none}
.ex-tf span{display:inline-block;min-width:54px;text-align:center;border:1.5px solid var(--line);border-radius:999px;padding:7px 10px;font-weight:700;font-size:14px;background:var(--paper)}
.ex-tf input:checked+span{background:var(--brand);border-color:var(--brand);color:var(--brand-ink)}
.ex-tf input:focus-visible+span{outline:3px solid var(--brand);outline-offset:2px}
.ex-key{font-style:normal;font-weight:700;color:var(--ok);white-space:nowrap}
.ex-tl .i{max-width:320px;font-size:16px}
.ex-tl .i.ok{border-color:var(--ok);background:var(--ok-soft)}
.ex-tl .i.bad{border-color:var(--bad);background:var(--bad-soft)}
.ex-fb{margin-top:10px;border-top:1px dashed var(--line);padding-top:10px;font-size:15px;line-height:1.5}
.ex-verdict{font-weight:700}
.is-ok .ex-verdict{color:var(--ok)} .is-bad .ex-verdict{color:var(--bad)} .is-part .ex-verdict{color:var(--warn)}
.ex-expl{margin-top:4px;color:var(--ink)}
.ex-foot{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.ex-score{display:flex;gap:16px;align-items:center;flex-wrap:wrap;border-radius:var(--r);padding:16px 20px;border:2px solid var(--line);background:var(--paper)}
.ex-score.hi{border-color:var(--ok);background:var(--ok-soft)}
.ex-score.mid{border-color:var(--warn);background:var(--warn-soft)}
.ex-score.lo{border-color:var(--bad);background:var(--bad-soft)}
.ex-score>div:nth-child(2){flex:1;min-width:180px}
.ex-big{font-size:44px;font-weight:800;line-height:1}
.ex-big small{font-size:18px;font-weight:700;opacity:.7}
.b-score{background:var(--ok-soft);color:var(--ok)}
.ex-guide{font-size:13px;background:var(--ground);border:1px solid var(--line);border-radius:10px;padding:10px 12px;margin:0;white-space:pre-wrap;font-family:ui-monospace,Menlo,Consolas,monospace}
@media (max-width:560px){
  .ex-q{padding:14px 12px}
  .ex-st{grid-template-columns:auto 1fr}
  .ex-tf{grid-column:1/-1;justify-content:flex-end}
  .ex-tf span{min-width:72px;padding:9px 12px}
  .ex-big{font-size:36px}
  .ex-foot .btn{width:100%}
}

/* ===== Công thức (KaTeX) ===== */
.katex{font-size:1.08em}
.mm-fo{color:inherit}
.mm-fo .katex{font-size:1.02em}
.mm-fo .katex-display{margin:0}
.ml .katex,.ex .katex,.rich .katex{font-size:1.06em}
.mt-err{color:var(--bad);font-size:.9em}
/* Bài tập theo nhánh + nút đáp án */
.ex-grp{display:flex;flex-direction:column;gap:12px}
.ex-gh{margin:6px 0 0;font-size:17px;font-weight:800;display:flex;gap:8px;align-items:center;padding:8px 12px;border-radius:12px;background:var(--brand-soft);color:var(--brand-deep)}
.ex-ansbtn{font-size:13px;padding:5px 10px;min-height:32px;white-space:nowrap}
.ex-q.is-shown{border-color:var(--brand);box-shadow:inset 4px 0 0 var(--brand)}
.ex-q.is-seen{opacity:.92}
.ex-q.is-shown .ex-verdict{color:var(--brand-deep)}
.ex-key.f{color:var(--bad)}

/* Trang bài học: video → bài tập ở cột trái, nội dung chính ở cột phải (bám theo khi cuộn) */
.lgrid{grid-template-areas:"vid main" "ex main";grid-template-rows:auto 1fr;align-items:start}
.lgrid>#secVid{grid-area:vid}
.lgrid>#secMain{grid-area:main;position:sticky;top:84px;max-height:calc(100vh - 100px);overflow:auto;overscroll-behavior:contain}
.lgrid>#secEx{grid-area:ex;margin-top:4px}
@media (max-width:900px){
  .lgrid{grid-template-columns:1fr;grid-template-areas:"vid" "main" "ex";grid-template-rows:auto}
  .lgrid>#secMain{position:static;max-height:none;overflow:visible}
}
/* Thẻ ý cấp 2 trong sơ đồ (tiêu đề + gạch đầu dòng) */
.mm-card .mm-ct{margin-bottom:1px}
.mm-card .mm-cl{margin:0;padding-left:18px;list-style:none}
.mm-card .mm-cl li{position:relative;margin:1px 0}
/* Ý lớn: ô vuông màu đậm, chữ đậm, cách nhau rõ */
.mm-card>.mm-cl>li{font-weight:700;margin-top:5px}
.mm-card>.mm-cl>li:first-child{margin-top:2px}
.mm-card>.mm-cl>li::before{content:"";position:absolute;left:-15px;top:.42em;width:9px;height:9px;border-radius:2.5px;background:var(--mmc,currentColor)}
/* Ý nhỏ: thụt vào, có đường gióng màu nhạt bên trái, gạch ngắn thay chấm, chữ thường */
.mm-card .mm-cl ul{position:relative;margin:1px 0 2px 2px;padding-left:14px;list-style:none;font-weight:400}
.mm-card .mm-cl ul::before{content:"";position:absolute;left:0;top:3px;bottom:3px;width:2px;border-radius:2px;background:var(--mmc,currentColor);opacity:.35}
.mm-card .mm-cl ul>li{color:var(--ink-2,inherit);font-weight:400}
.mm-card .mm-cl ul>li::before{content:"";position:absolute;left:-9px;top:.72em;width:6px;height:2px;border-radius:1px;background:var(--mmc,currentColor);opacity:.8}
/* Sơ đồ trên trang bài học: rộng hơn khung chữ để tranh toàn cảnh to nhất */
@media (min-width:1200px){
  #secMap{width:min(calc(100vw - 48px),1560px);margin-left:calc(50% - min(50vw - 24px,780px))}
}
.mm-card .mm-cl.c2{column-count:2;column-gap:22px}
.mm-card .mm-cl.c2>li{break-inside:avoid}
/* Sơ đồ kiểu dọc (điện thoại): cuộn trang tự nhiên, không kéo/phóng */
.mm.mm-stack .mm-stage{touch-action:auto;cursor:default;user-select:text;-webkit-user-select:text}
.mm.mm-stack .mm-stage svg{margin:0 auto}
.mm.mm-stack .mm-maptools{display:none}
.mm.mm-full.mm-stack .mm-stage{overflow:auto;-webkit-overflow-scrolling:touch}
/* Toàn màn hình thật (máy tính) */
.mm:fullscreen{background:var(--paper);padding:10px;display:flex;flex-direction:column;gap:8px}
.mm:fullscreen .mm-stage{flex:1;height:auto!important}
/* Chế độ học từng nhánh trên điện thoại */
.mm-study[hidden]{display:none}
.mm.mm-studying{display:flex;flex-direction:column}
.mm.mm-studying .mm-stage,.mm.mm-studying .mm-list,.mm.mm-studying .mm-hint,.mm.mm-studying .seg2,.mm.mm-studying .mm-maptools{display:none!important}
.mm.mm-studying .mm-bar{margin:0}
.mm-study{flex:1;min-height:0;display:flex;flex-direction:column;gap:10px}
.st-top{display:flex;align-items:center;gap:8px;font-size:14px;color:var(--muted)}
.st-title{flex:1;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-weight:700}
.st-pg{flex:none;font-weight:800;color:var(--ink);background:var(--soft);border-radius:999px;padding:3px 10px}
.st-body{flex:1;min-height:0;overflow:auto;-webkit-overflow-scrolling:touch;overscroll-behavior:contain;font-size:19px;line-height:1.55}
.st-root{background:var(--mm-root);color:var(--mm-root-ink);border-radius:18px;padding:18px;text-align:center;font-size:24px;font-weight:800;line-height:1.3}
.st-tip{color:var(--muted);font-size:15px;margin:14px 2px 8px}
.st-toc{display:flex;flex-direction:column;gap:10px}
.st-toc button{text-align:left;border:0;border-radius:14px;padding:14px 16px;font:inherit;font-size:18px;font-weight:700;background:var(--c);color:var(--ci);min-height:52px}
.st-card{border:2px solid var(--c);border-radius:18px;background:color-mix(in srgb,var(--c) 9%,var(--paper));padding:14px 16px 18px}
.st-h{margin:0 0 8px;font-size:22px;line-height:1.3;padding:10px 14px;border-radius:12px;background:var(--c);color:var(--ci)}
.st-l{margin:0;padding-left:22px}
.st-l li{margin:6px 0}
.st-l.d2>li{font-weight:700}
.st-l.d2>li::marker{color:var(--c)}
.st-l.d3{padding-left:20px}
.st-l.d3>li{font-weight:400}
.st-l .katex{font-size:1.05em}
.st-nav{display:flex;align-items:center;gap:8px;padding-top:4px}
.st-nav .btn{min-height:48px;min-width:96px;font-size:16px}
.st-dots{flex:1;display:flex;justify-content:center;gap:6px;flex-wrap:wrap}
.st-dots i{width:9px;height:9px;border-radius:50%;background:var(--line)}
.st-dots i.on{background:var(--c,var(--mm-root));transform:scale(1.35)}
/* Bấm nhánh để phóng to */
.mm-node.zoomable{cursor:zoom-in}
.mm .mm-tg{cursor:pointer}
.mm-stage svg.mm-anim{transition:transform .38s cubic-bezier(.2,.7,.2,1)}
.mm-back{position:absolute;top:10px;right:10px;z-index:3;border:0;border-radius:999px;padding:9px 16px;font:700 14px/1 var(--font);background:var(--ink);color:var(--paper);box-shadow:0 6px 18px rgba(0,0,0,.18);cursor:pointer}
.mm-back[hidden]{display:none}

/* ===== Hình minh họa ===== */
.fig-sec .sh{margin-bottom:4px}
.fig-grp{margin-top:12px}
.fig-gh{margin:0 0 8px;font-size:16px;font-weight:800;color:var(--brand-deep)}
.fig-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.fig{margin:0;background:var(--paper);border:1px solid var(--line);border-radius:var(--r);overflow:hidden;cursor:zoom-in;display:flex;flex-direction:column;transition:box-shadow .15s,transform .15s}
.fig:hover,.fig:focus-visible{box-shadow:var(--shadow);transform:translateY(-2px);outline:none}
.fig-img{background:#fff;padding:6px;display:grid;place-items:center}
.fig-img img{width:100%;height:auto;display:block}
.fig figcaption{padding:10px 12px 12px;display:flex;flex-direction:column;gap:3px;font-size:14px;line-height:1.45;border-top:1px solid var(--line)}
.fig figcaption span{color:var(--muted)}
.fig-lb{position:fixed;inset:0;z-index:200;background:rgba(10,20,30,.72);display:grid;place-items:center;padding:14px}
.fig-lb-box{background:var(--paper);border-radius:16px;max-width:min(1100px,100%);max-height:100%;overflow:auto;padding:14px 16px;display:flex;flex-direction:column;gap:8px}
.fig-lb-h{display:flex;gap:12px;align-items:flex-start;justify-content:space-between;font-size:17px}
.fig-br{font-size:13px;color:var(--muted);font-weight:700}
.fig-lb-img{background:#fff;border-radius:10px}
.fig-lb-img img{width:100%;height:auto;display:block;max-height:78vh;object-fit:contain}
.fig-cap{margin:0;color:var(--ink);font-size:15px;line-height:1.5}
.st-figs{display:flex;flex-direction:column;gap:12px;margin-top:14px}
.st-fig{cursor:default}
.st-fig figcaption{font-size:15px}
@media (max-width:560px){.fig-grid{grid-template-columns:1fr}}

/* Hình minh họa nằm ngay trong thẻ nhánh của sơ đồ */
.mm-figs{display:flex;flex-wrap:wrap;gap:8px;margin-top:8px;justify-content:center}
.mm-fig{display:block;box-sizing:border-box;background:#fff;border:1.5px solid var(--mmc,var(--line));border-radius:8px;padding:2px;cursor:zoom-in;transition:box-shadow .15s}
.mm-fig:hover{box-shadow:0 2px 10px rgba(0,0,0,.18)}
/* Chế độ học (điện thoại): ý lớn ô vuông màu, ý nhỏ gạch ngắn + đường gióng */
.st-l{list-style:none}
.st-l li{position:relative}
.st-l.d2>li{margin-top:12px}
.st-l.d2>li::before{content:"";position:absolute;left:-19px;top:.45em;width:11px;height:11px;border-radius:3px;background:var(--c)}
.st-l.d3{position:relative;margin:4px 0 2px 2px;padding-left:18px}
.st-l.d3::before{content:"";position:absolute;left:0;top:4px;bottom:4px;width:3px;border-radius:2px;background:var(--c);opacity:.35}
.st-l.d3>li{margin:4px 0}
.st-l.d3>li::before{content:"";position:absolute;left:-12px;top:.78em;width:7px;height:2.5px;border-radius:2px;background:var(--c)}
/* Bài tập: chọn mức độ */
.ex-lvbox{margin:0 0 12px}
.ex-lvh{font-size:14px;color:var(--muted);margin:0 0 8px;font-weight:600}
.ex-lv{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}
.ex-lv button{display:flex;flex-direction:column;align-items:center;gap:2px;border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:14px;padding:10px 6px;font:inherit;cursor:pointer;min-height:58px;transition:border-color .15s,background .15s}
.ex-lv .lvn{font-weight:800;font-size:16px;white-space:nowrap}
.ex-lv .lvs{font-size:12.5px;color:var(--muted)}
.ex-lv button.lv1{--lc:#16a34a}.ex-lv button.lv2{--lc:#2563eb}.ex-lv button.lv3{--lc:#9333ea}.ex-lv button.lv4{--lc:#e11d48}
.ex-lv button:hover{border-color:var(--lc)}
.ex-lv button.on{border-color:var(--lc);background:color-mix(in srgb,var(--lc) 12%,var(--paper))}
.ex-lv button.on .lvn{color:var(--lc)}
.ex-acts{display:flex;gap:8px;flex-wrap:wrap}
@media (max-width:560px){.ex-lv{grid-template-columns:repeat(2,1fr)}.ex-lv .lvn{font-size:15px}}
/* Hình minh hoạ trong câu hỏi bài tập: vừa phải, không lấn át câu hỏi */
.ex-fig{display:block;margin:8px auto 10px;padding:6px;border:1px solid var(--line);border-radius:12px;background:#fff;cursor:zoom-in;max-width:min(420px,100%)}
.ex-fig img{display:block;width:100%;height:auto;max-height:220px;object-fit:contain}
.ex-fig:hover{box-shadow:0 2px 10px rgba(0,0,0,.12)}
@media (max-width:560px){.ex-fig img{max-height:190px}}
/* vectơ trong chú thích hình: mũi tên phía trên chữ */
.vec{display:inline-block;position:relative;padding-top:.32em;line-height:1}
.vec::before{content:"";position:absolute;left:0;right:0;top:.02em;height:.36em;background:no-repeat center/100% 100% url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 8' preserveAspectRatio='none'%3E%3Cpath d='M0 4H18M14 1l5 3-5 3' fill='none' stroke='%23334' stroke-width='1.6'/%3E%3C/svg%3E")}
/* Bảo vệ nội dung (xem protect.js) */
.protect .mm, .protect .lsec, .protect .fig-lb, .protect .ex-text, .protect .ex-opt, .protect .ex-fb, .protect .mm-study{-webkit-user-select:none;user-select:none;-webkit-touch-callout:none}
.protect input, .protect textarea{-webkit-user-select:text;user-select:text}
.protect img, .protect svg{-webkit-user-drag:none}
.wm{position:absolute;inset:0;pointer-events:none;z-index:4;background-repeat:repeat}
.fig-lb-img{position:relative}
@media print{ body.printing-blocked *{visibility:hidden} .protect{display:none!important} body::after{content:"Nội dung bài học có bản quyền — vui lòng học trực tuyến trên website.";display:block;font:16px/1.5 Arial;padding:40px;visibility:visible} }
.seo-links{max-width:1100px;margin:0 auto;padding:6px 16px 24px;font-size:13px;color:var(--muted);text-align:center;line-height:2}
.seo-links a{color:var(--muted);text-decoration:none;white-space:nowrap}
.seo-links a:hover{text-decoration:underline}
/* nút nghe đọc tiếng Anh trên sơ đồ */
.mm-say{display:inline-block;border:0;margin:0 0 0 4px;padding:0 3px;font-size:.68em;line-height:1.5;border-radius:6px;cursor:pointer;background:transparent;opacity:.6;vertical-align:.1em;filter:grayscale(.3)}
.mm-say:hover,.mm-say.on{opacity:1;filter:none;background:color-mix(in srgb,var(--mmc,var(--c,#0EA5E9)) 25%,#fff)}
.st-l .mm-say{font-size:.9em;padding:2px 8px}
/* ---- Trò chơi tiểu học ---- */
.gm-pick{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:10px}
.gm-pick button{display:flex;flex-direction:column;align-items:flex-start;gap:4px;text-align:left;border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:18px;padding:14px;font:inherit;cursor:pointer}
.gm-pick button:hover,.gm-pick button.on{border-color:#F59E0B;background:color-mix(in srgb,#F59E0B 10%,var(--paper))}
.gm-pick .gm-ic{font-size:34px;line-height:1}.gm-pick b{font-size:18px}.gm-pick small{color:var(--muted);font-size:14px;line-height:1.4}
.gm-stage{position:relative;overflow:hidden;margin-top:14px;border:2px dashed color-mix(in srgb,#F59E0B 55%,var(--line));border-radius:20px;padding:16px;background:color-mix(in srgb,#FEF3C7 45%,var(--paper));min-height:200px}
.gm-top{display:flex;justify-content:space-between;gap:10px;font-weight:700;color:var(--muted);margin-bottom:10px;flex-wrap:wrap}
.gm-tree{letter-spacing:2px}
.gm-q,.gm-item{font-size:22px;font-weight:700;line-height:1.4;margin:6px 0 14px}
.gm-item{display:inline-block;background:var(--paper);border:2px solid #F59E0B;border-radius:16px;padding:12px 18px;box-shadow:0 4px 0 #F59E0B}
.gm-opts,.gm-baskets{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:10px}
.gm-opts button,.gm-baskets button{display:flex;align-items:center;gap:10px;min-height:58px;border:2px solid var(--line);border-radius:16px;background:var(--paper);color:var(--ink);font:inherit;font-size:19px;font-weight:600;padding:10px 14px;cursor:pointer;text-align:left;transition:transform .1s}
.gm-opts button:active,.gm-baskets button:active{transform:scale(.97)}
.gm-opts i{font-style:normal;display:grid;place-items:center;width:30px;height:30px;border-radius:50%;background:var(--soft);font-weight:800;flex:none}
.gm-baskets button span{font-size:26px}
.gm-opts .ok,.gm-baskets .ok{border-color:#10B981;background:#D1FAE5}
.gm-opts .bad,.gm-baskets .bad{border-color:#F43F5E;background:#FFE4E6;animation:gm-shake .35s}
.gm-msg{min-height:30px;margin-top:10px;font-weight:700;font-size:18px}.gm-ex{font-weight:400;font-size:16px;margin-top:4px}
.gm-ask{margin:0 0 8px;font-weight:700;color:var(--muted)}
.gm-cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(130px,1fr));gap:10px}
.gm-card{position:relative;min-height:96px;border:0;border-radius:16px;padding:0;background:transparent;cursor:pointer;font:inherit;perspective:600px}
.gm-card span{position:absolute;inset:0;display:grid;place-items:center;border-radius:16px;padding:8px;backface-visibility:hidden;transition:transform .35s;font-weight:700;font-size:17px;line-height:1.3}
.gm-card .f{background:linear-gradient(135deg,#F59E0B,#F43F5E);color:#fff;font-size:32px}
.gm-card .b{transform:rotateY(180deg);background:var(--paper);border:2px solid #3B82F6;color:var(--ink)}.gm-card .b.sb{border-color:#A855F7}
.gm-card.up .f{transform:rotateY(180deg)}.gm-card.up .b{transform:rotateY(0)}
.gm-card.done .b{border-color:#10B981;background:#D1FAE5}
.gm-end{text-align:center;padding:10px}.gm-end .gm-big{font-size:60px}.gm-end b{font-size:22px;display:block}.gm-end p{color:var(--muted)}
.gm-stage .gm-end{position:relative;z-index:2}
.gm-conf{position:absolute;inset:0;pointer-events:none;z-index:3}
.gm-conf i{position:absolute;top:-10px;width:10px;height:14px;border-radius:2px;animation:gm-fall 1.8s ease-in forwards}
@keyframes gm-fall{to{top:110%;opacity:.2}}
@keyframes gm-shake{25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}
@media (max-width:560px){.gm-q,.gm-item{font-size:19px}.gm-opts button,.gm-baskets button{font-size:17px}}

/* ---------- Chuyên đề ---------- */
.ex-lvc{font-size:12px;font-weight:700;border-radius:999px;padding:2px 9px;border:1px solid var(--lc);color:var(--lc)}
.ex-lvc.lv1{--lc:#16a34a}.ex-lvc.lv2{--lc:#2563eb}.ex-lvc.lv3{--lc:#9333ea}.ex-lvc.lv4{--lc:#e11d48}
.cd-entry{background:linear-gradient(135deg,var(--brand-soft),var(--paper));border:1px solid var(--line);border-radius:16px;padding:14px;margin:12px 0}
.cd-eh{margin-bottom:10px}
.cd-elist{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:10px}
.cd-ecard{display:flex;gap:10px;align-items:center;background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:10px 12px;color:inherit;text-decoration:none}
.cd-ecard:hover{border-color:var(--brand)}
.cd-ecard .ic{font-size:24px}.cd-ecard b{display:block}
.cd-toc{display:flex;flex-wrap:nowrap;gap:8px;margin:10px 0 14px;position:sticky;top:0;z-index:8;background:var(--ground);padding:8px 0;overflow-x:auto;scrollbar-width:thin;width:100%;max-width:100%;min-width:0;contain:inline-size;align-items:center}
.cd-toc button{display:flex;gap:8px;align-items:center;text-align:left;border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:10px;padding:7px 11px;font:inherit;font-size:14px;cursor:pointer;max-width:100%}
.cd-toc button:hover{border-color:var(--brand)}
.cd-toc .n{background:var(--brand);color:#fff;border-radius:6px;min-width:22px;height:22px;display:grid;place-items:center;font-size:12px;font-weight:800;flex:none}
.cd-dang{background:var(--paper);border:1px solid var(--line);border-radius:16px;padding:16px;margin:16px 0}
.cd-h{font-size:19px;margin:0 0 12px;display:flex;gap:10px;align-items:baseline;flex-wrap:wrap}
.cd-n{background:var(--brand);color:#fff;border-radius:8px;padding:2px 10px;font-size:14px;flex:none}
.cd-th{display:flex;flex-direction:column;gap:12px}
.cd-box{border-radius:12px;padding:12px 14px;border-left:5px solid var(--bc);background:var(--bg)}
.cd-box p{margin:6px 0}.cd-box ol,.cd-box ul{margin:6px 0;padding-left:22px;display:flex;flex-direction:column;gap:5px}
.cd-bh{font-weight:800;margin-bottom:4px}
.cd-pp{--bc:var(--brand);--bg:var(--brand-soft)}
.cd-note{--bc:var(--warn);--bg:var(--warn-soft)}
.cd-vd{--bc:var(--ok);--bg:var(--soft)}
.cd-step b{color:var(--brand-deep)}
.cd-sol{margin-top:8px}
.cd-sol summary{cursor:pointer;font-weight:700;color:var(--ok);padding:6px 0;list-style:none}
.cd-sol summary::-webkit-details-marker{display:none}
.cd-sol[open] summary{color:var(--muted)}
.cd-solb{background:var(--paper);border:1px dashed var(--line);border-radius:10px;padding:8px 12px}
.cd-fig{display:block;margin:8px auto}
.cd-prac{margin-top:14px;display:flex;flex-direction:column;gap:12px}
.cd-prac>.btn{align-self:flex-start}
@media (max-width:600px){.cd-dang{padding:12px}.cd-h{font-size:17px}.cd-prac>.btn{align-self:stretch}}
.ex-h{flex-wrap:wrap;row-gap:6px}.ex-lvc,.ex-tag,.ex-n{white-space:nowrap}
.ex-expl .ex-el+.ex-el{margin-top:4px}
.ex-expl>.ex-el:first-child::before{content:"💡 "}
.ex-xfig{display:block;margin:8px 0;max-width:min(420px,100%)}
.ex-lv button.lvcd{--lc:#d97706}
.ex-lv:has(.lvcd){grid-template-columns:repeat(5,1fr)}
.ex-lv button.lvcd{border-style:dashed}.ex-lv button.lvcd.on{border-style:solid}
@media (max-width:560px){.ex-lv:has(.lvcd){grid-template-columns:repeat(2,1fr)}.ex-lv button.lvcd{grid-column:1/-1}}
/* Bài học: Sơ đồ → Video → Bài tập → (Trò chơi) → Ý chính (xếp dọc) */
.lgrid{display:flex!important;flex-direction:column;gap:18px}
.lgrid>#secVid{order:1}.lgrid>#secEx{order:2;margin-top:0}.lgrid>#secGame{order:3}.lgrid>#secMain{order:4;position:static;max-height:none;overflow:visible}
.lgrid>#secVid #vidBox{max-width:860px}
.pn.pn-top{margin:4px 0 14px}
.pn .btn{max-width:48%;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;display:inline-block}
.pn .pn-l{font-size:12px;color:var(--muted);display:block;font-weight:600}
.pn,.pn.pn-top{flex-direction:row!important;flex-wrap:nowrap}
.pn .btn{flex:0 1 48%;min-width:0;text-align:left}
.pn .btn:last-child:not(:first-child){text-align:right}
@media (max-width:600px){.pn .btn{white-space:normal;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;font-size:13.5px;padding:8px 10px}}
.pn .pn-t{display:block;overflow:hidden;text-overflow:ellipsis}
@media (max-width:600px){.pn .btn{display:block}.pn .pn-t{display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;white-space:normal}}
/* Máy tính: hình lời giải to hơn để đọc rõ chữ */
@media (min-width:700px){
  .ex-xfig,.cd-solb .ex-fig,.cd-vd .ex-fig{width:min(720px,100%);max-width:100%;margin:10px 0}
  .ex-xfig img,.cd-solb .ex-fig img,.cd-vd .ex-fig img{max-height:460px}
  .ex-q>.ex-fig{width:min(540px,100%);max-width:100%}
  .ex-q>.ex-fig img{max-height:300px}
}
.cd,.ex-sec,#exBox{overflow-anchor:none}
footer .ftr-links{flex-basis:100%;font-size:13px}footer .ftr-links a{color:inherit}
/* ===== Trò chơi v2: laptop chia 2 cột (menu trái – sân chơi phải), điện thoại 1 cột ===== */
.lgrid>#secGame,#gmBox{width:100%}
.gm{display:grid;grid-template-columns:300px 1fr;gap:16px;align-items:start}
.gm-side{display:flex;flex-direction:column;gap:10px}
.gm-lv{display:flex;flex-wrap:wrap;gap:6px;align-items:center;font-weight:700;color:var(--muted)}
.gm-lv button{border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:999px;padding:6px 12px;font:inherit;font-weight:700;cursor:pointer}
.gm-lv button.on{border-color:#F59E0B;background:#FEF3C7;color:#92400E}
.gm .gm-pick{display:flex;flex-direction:column;gap:8px}
.gm .gm-pick button{flex-direction:row;align-items:center;gap:12px;padding:12px}
.gm .gm-pick button>span:last-child{display:flex;flex-direction:column;gap:2px}
.gm .gm-stage{margin-top:0;min-height:360px;display:flex;flex-direction:column;justify-content:center}
.gm-hello,.gm-intro{text-align:center;padding:10px}
.gm-hello .gm-big,.gm-intro .gm-big{font-size:56px;line-height:1.1}
.gm-hello .gm-ttl,.gm-intro>b{font-size:22px;display:block;margin:6px 0}
.gm-hello p{color:var(--muted);font-size:17px}
.gm-lvtag{display:inline-block;background:#FEF3C7;color:#92400E;border-radius:999px;padding:3px 12px;font-weight:700}
.gm-how{text-align:left;max-width:460px;margin:14px auto;font-size:18px;line-height:1.55;padding-left:26px}
.gm-how li{margin:4px 0}
.gm-time{display:flex;align-items:center;gap:8px;margin:4px 0 8px}
.gm-time>div{flex:1;height:10px;background:var(--soft);border-radius:99px;overflow:hidden}
.gm-time i{display:block;height:100%;background:#10B981;border-radius:99px;transition:width 1s linear}
.gm-time i.low{background:#F43F5E}.gm-time b{min-width:36px;text-align:right}
.gm-lane{display:flex;align-items:center;gap:8px;margin-bottom:6px}
.gm-who{width:62px;font-weight:700;font-size:14px;color:var(--muted)}
.gm-road{position:relative;flex:1;display:flex;gap:3px;height:38px;align-items:center;background:#E5E7EB;border-radius:10px;padding:0 4px}
.gm-road i{flex:1;height:4px;background:#fff;border-radius:2px;opacity:.8}.gm-road i.on{background:#F59E0B}
.gm-car{position:absolute;top:1px;font-size:28px;transition:left .6s cubic-bezier(.3,1.4,.6,1);transform:scaleX(-1)}
.gm-flag{font-size:22px}
.gm-opts button span{flex:1}
.gm-balloon{display:flex;gap:12px;align-items:center;background:var(--paper);border:3px solid #A855F7;border-radius:24px;padding:16px 18px;margin:8px 0 14px;font-size:21px;font-weight:700;line-height:1.45;box-shadow:0 5px 0 #A855F7}
.gm-balloon>span{font-size:40px;animation:gm-float 2s ease-in-out infinite}
@keyframes gm-float{50%{transform:translateY(-6px)}}
.gm-tf{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.gm-tf button{min-height:66px;border-radius:18px;border:0;font:inherit;font-size:22px;font-weight:800;color:#fff;cursor:pointer;box-shadow:0 5px 0 rgba(0,0,0,.18)}
.gm-tf .t{background:#10B981}.gm-tf .f{background:#F43F5E}
.gm-tf button:active{transform:translateY(3px);box-shadow:0 2px 0 rgba(0,0,0,.18)}
.gm-tf button.ok{outline:4px solid #FACC15}.gm-tf button.bad{animation:gm-shake .35s;outline:4px solid #111}
.gm-tf button:disabled{opacity:.75;cursor:default}
.gm-hearts{letter-spacing:2px}
.gm-cards.n3{grid-template-columns:repeat(3,1fr)}.gm-cards.n4{grid-template-columns:repeat(4,1fr)}
@media (max-width:860px){
  .gm{grid-template-columns:1fr}
  .gm .gm-stage{min-height:260px}
  .gm-cards.n3,.gm-cards.n4{grid-template-columns:repeat(2,1fr)}
  .gm-how{font-size:16px}.gm-balloon{font-size:18px}
}
.gm-lv{display:grid;grid-template-columns:repeat(3,1fr);gap:6px}.gm-lv>span{grid-column:1/-1;font-size:15px}
.gm-lv button{padding:6px 4px;font-size:15px}
/* ===== Thanh toán: điện thoại xếp dọc, không bị bóp chữ ===== */
.qr .qr-save{margin-top:10px;width:100%}
@media (max-width:560px){
  .pay2{grid-template-columns:1fr!important}
  .pay2 .qr{max-width:260px;margin:0 auto;width:100%}
  .pay2 .kv{grid-template-columns:auto minmax(0,1fr)!important;font-size:16px}
  .paybox{padding:16px}
}
/* ===== Đăng ký / đăng nhập ===== */
.seg3{display:grid;grid-template-columns:repeat(3,1fr);gap:6px}
.seg3 button{border:2px solid var(--line);background:var(--paper);color:var(--ink);border-radius:12px;padding:10px 4px;font:inherit;font-weight:700;font-size:14px;cursor:pointer}
.seg3 button.on{border-color:var(--pri,#0EA5E9);background:color-mix(in srgb,#0EA5E9 12%,var(--paper))}
.pw{position:relative;display:block}.pw .i{padding-right:48px;width:100%}
.pw .pw-eye{position:absolute;right:4px;top:50%;transform:translateY(-50%)}
.adm-subj{display:flex;flex-wrap:wrap;gap:6px}
.adm-subj button{border:1.5px solid var(--line);background:var(--paper);color:var(--ink);border-radius:999px;padding:6px 12px;font:inherit;font-size:14px;font-weight:600;cursor:pointer}
.adm-subj button span{color:var(--muted);font-weight:500;margin-left:2px}
.adm-subj button.on{border-color:#0EA5E9;background:color-mix(in srgb,#0EA5E9 12%,var(--paper))}
.qr .qr-share{margin-top:8px;width:100%}
.shr-btn{display:inline-flex;align-items:center;gap:6px;border:1.5px solid #0EA5E9;background:var(--paper,#fff);color:#0369A1;border-radius:999px;padding:6px 14px;font:inherit;font-weight:700;font-size:15px;cursor:pointer}
/* Nút Tải PowerPoint + Chia sẻ: máy tính nằm cùng hàng thanh công cụ sơ đồ, điện thoại nằm dưới sơ đồ */
.lx-acts{display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.lx-acts.in-bar{margin-left:auto}
.lx-acts.in-bar + .mm-fullbtn{margin-left:0}
.lx-acts.below{justify-content:center;margin-top:10px}
.lx-acts.below > *{flex:1 1 150px;justify-content:center;text-align:center}
.lx-acts .btn.sm,.lx-acts .shr-btn{min-height:38px}

/* Video bài tập ngắn (YouTube Shorts) */
.shorts{display:flex;gap:12px;overflow-x:auto;scroll-snap-type:x mandatory;padding:4px 2px 10px;-webkit-overflow-scrolling:touch}
.short{flex:0 0 min(44vw,210px);aspect-ratio:9/16;position:relative;border:0;padding:0;border-radius:var(--r);overflow:hidden;background:#000;cursor:pointer;scroll-snap-align:start;box-shadow:0 2px 10px rgba(0,0,0,.12)}
.short img{width:100%;height:100%;object-fit:cover;display:block}
.short .play{position:absolute;inset:0;margin:auto;width:56px;height:56px;border-radius:50%;background:rgba(0,0,0,.55);color:#fff;display:grid;place-items:center;font-size:22px;padding-left:4px}
.short .st{position:absolute;left:0;right:0;bottom:0;padding:28px 10px 10px;color:#fff;font-size:13px;line-height:1.3;font-weight:700;text-align:left;background:linear-gradient(transparent,rgba(0,0,0,.85))}
.short iframe{position:absolute;inset:0;width:100%;height:100%;border:0;background:#000}
.short.on .play,.short.on .st{display:none}
.lgrid>#secShorts{grid-area:vid;min-width:0}
/* Cửa sổ xem video ngắn */
.sv-modal{position:fixed;inset:0;z-index:1000;background:rgba(8,12,24,.92);display:flex;align-items:center;justify-content:center;padding:12px}
.sv-box{position:relative;height:min(88vh,calc((100vw - 24px)*16/9));aspect-ratio:9/16;max-width:100%;background:#000;border-radius:14px;overflow:hidden;box-shadow:0 10px 40px rgba(0,0,0,.5)}
.sv-box iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.sv-x{position:absolute;top:12px;right:14px;width:44px;height:44px;border-radius:50%;border:0;background:rgba(255,255,255,.15);color:#fff;font-size:22px;cursor:pointer}
.sv-nav{position:absolute;top:50%;transform:translateY(-50%);width:48px;height:64px;border:0;border-radius:12px;background:rgba(255,255,255,.15);color:#fff;font-size:40px;line-height:1;cursor:pointer}
.sv-nav:disabled{opacity:.25;cursor:default}
.sv-prev{left:14px}.sv-next{right:14px}
.sv-cap{position:absolute;bottom:10px;left:0;right:0;text-align:center;color:#e2e8f0;font-size:13px;padding:0 70px}
@media (max-width:700px){.sv-nav{top:auto;bottom:40px;transform:none}.sv-cap{bottom:110px}}

/* Khung chọn mức độ bài tập: dính ở trên khi kéo xuống, thu gọn cho đỡ che bài */
.ex-lvbox{min-width:0;max-width:100%;position:sticky;top:calc(var(--hdrH,64px) - 1px);z-index:9;background:var(--ground);padding:6px 0 8px;margin:0 0 12px;box-shadow:0 -8px 0 var(--ground)}
.ex-lvbox.stuck{box-shadow:0 -8px 0 var(--ground),0 10px 14px -12px rgba(0,0,0,.35)}
.ex-lvbox.stuck .ex-lvh{display:none}
.ex-lvbox.stuck .ex-lv button{min-height:0;padding:6px 4px;border-radius:12px}
.ex-lvbox.stuck .ex-lv .lvs{display:none}
.ex-lvbox.stuck .ex-lv .lvn{font-size:14.5px}
/* Điện thoại: khi dính, tất cả nút nằm gọn trên 1 hàng, luôn vừa bề ngang màn hình (không bao giờ làm trang rộng ra) */
@media (max-width:560px){
  .ex-lvbox.stuck .ex-lv,.ex-lvbox.stuck .ex-lv:has(.lvcd){grid-template-columns:repeat(var(--nlv,4),minmax(0,1fr));gap:4px}
  .ex-lvbox.stuck .ex-lv button.lvcd{grid-column:auto}
  .ex-lvbox.stuck .ex-lv button{padding:5px 2px;border-radius:10px;min-width:0}
  .ex-lvbox.stuck .ex-lv .lvn{font-size:12.5px;white-space:normal;line-height:1.15;text-align:center;overflow-wrap:normal;word-break:keep-all}
}
@media (max-width:380px){.ex-lvbox.stuck .ex-lv .lvn{font-size:11.5px;letter-spacing:-.2px}}
.ex-sec,#exBox,.ex-lvbox,.ex-lv{min-width:0;max-width:100%}
.ex-sec{overflow-x:clip}
/* Điện thoại: chạm nhanh 2 lần vào nút không làm trang tự phóng to; ô nhập chữ ≥16px để iPhone không tự phóng */
button,a,[role="button"],.ex-lv button,.ex-q label{touch-action:manipulation}
@media (max-width:700px){input,select,textarea{font-size:16px!important}}
/* Quản trị: bấm số tiền để xem chi tiết lần nạp */
.amt-link{border:0;background:none;padding:0;font:inherit;color:var(--brand,#0369a1);font-weight:700;text-decoration:underline dotted;text-underline-offset:3px;cursor:pointer}
.tdl{display:flex;flex-direction:column;gap:12px;max-height:65vh;overflow:auto}
.tdl-g{display:flex;flex-direction:column;gap:4px;padding:10px 12px;border:1px solid var(--line);border-radius:12px;background:var(--paper)}
.tdl-l{margin:4px 0 0;padding-left:18px;display:flex;flex-direction:column;gap:4px}
.tdl-l li.hl{background:color-mix(in srgb,#16a34a 10%,transparent);border-radius:6px;padding:2px 4px}
/* Chuyên đề: thanh chọn dạng (dính khi kéo xuống) + nút chuyển dạng */
.cd-toc .cd-tl{flex:none;font-size:13px;font-weight:700;color:var(--muted)}
.cd-toc button{flex:none;max-width:260px}
.cd-toc button .t{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;min-width:0}
.cd-toc button.on{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 12%,var(--paper));font-weight:700;box-shadow:inset 0 -3px 0 var(--brand)}
.cd-toc.stuck{box-shadow:0 10px 14px -12px rgba(0,0,0,.35)}
.cd-toc.stuck .cd-tl{display:none}
.cd-nav{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;margin-top:16px;padding-top:12px;border-top:1px dashed var(--line)}
.cd-nav .btn{max-width:100%;white-space:normal;text-align:left}
@media (max-width:600px){.cd-toc button{max-width:170px;padding:6px 9px;font-size:13px}.cd-toc.stuck button .t{max-width:90px}.cd-nav{flex-direction:column-reverse}.cd-nav .btn{width:100%;text-align:center}}
/* Quản trị › Bài học: lọc theo video ngắn / PowerPoint */
.adm-media{display:flex;flex-wrap:wrap;gap:6px}
.adm-media button{border:1px solid var(--line);background:var(--paper);border-radius:999px;padding:5px 11px;font:inherit;font-size:13px;font-weight:600;cursor:pointer;color:var(--ink)}
.adm-media button span{color:var(--muted);font-weight:700;margin-left:2px}
.adm-media button.on{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 12%,var(--paper))}
.t th.c,.t td.c{text-align:center}
/* Combo theo môn: thanh mua nhanh dưới tên môn ở trang lớp */
.scombo{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:-4px 0 10px;padding:8px 12px;border:1.5px dashed color-mix(in srgb,var(--brand) 55%,var(--line));border-radius:12px;background:color-mix(in srgb,var(--brand) 6%,var(--paper));font-size:14px}
.scombo .sp{flex:1}