:root{
  --navy:#1F3864; --navy-2:#2b4a80; --teal:#0E7C86; --teal-soft:#e3f3f4; --gold:#B8860B; --gold-soft:#fbf3dc;
  --ink:#1c2230; --muted:#5d6678; --line:#dfe3ea; --bg:#f4f6fa; --card:#fff; --ok:#1d7f4e; --ok-soft:#e5f5ec;
  --bad:#b3261e; --bad-soft:#fdeceb; --warn:#9a6700; --warn-soft:#fff6dd; --radius:12px;
  --side:280px; --top:60px; --shadow:0 1px 2px rgba(20,30,60,.06),0 4px 16px rgba(20,30,60,.06);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Be Vietnam Pro",system-ui,Segoe UI,Arial,sans-serif;color:var(--ink);background:var(--bg);font-size:15px;line-height:1.6}
a{color:var(--teal);text-decoration:none} a:hover{text-decoration:underline}
img{max-width:100%;height:auto}
h1,h2,h3,h4{color:var(--navy);line-height:1.3;margin:1.2em 0 .5em}
h1{font-size:1.65rem;margin-top:.2em} h2{font-size:1.3rem} h3{font-size:1.1rem} h4{font-size:1rem}
small{color:var(--muted)}
/* ---------- topbar ---------- */
.topbar{position:fixed;inset:0 0 auto 0;height:var(--top);background:var(--navy);color:#fff;display:flex;align-items:center;gap:12px;padding:0 16px;z-index:40;box-shadow:0 2px 8px rgba(0,0,0,.15)}
.brand{display:flex;align-items:center;gap:10px;color:#fff;min-width:0}
.brand:hover{text-decoration:none}
.brand img{border-radius:50%;background:#fff;flex:none}
.brand span{display:flex;flex-direction:column;line-height:1.2;min-width:0}
.brand b{font-size:.98rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.brand small{color:#c9d4ea;font-size:.75rem}
.top-right{margin-left:auto;display:flex;align-items:center;gap:8px}
.who{display:flex;flex-direction:column;text-align:right;line-height:1.15;font-size:.88rem;margin-right:6px}
.who small{color:#c9d4ea;font-size:.74rem}
.menu-btn{display:none;background:none;border:0;color:#fff;font-size:1.4rem;cursor:pointer;padding:4px 8px}
/* ---------- sidebar ---------- */
.sidebar{position:fixed;top:var(--top);left:0;bottom:0;width:var(--side);background:#fff;border-right:1px solid var(--line);overflow-y:auto;padding:12px 10px 40px;z-index:30}
.nav-group{font-size:.72rem;text-transform:uppercase;letter-spacing:.04em;color:var(--gold);font-weight:700;margin:16px 8px 6px;line-height:1.35}
.nav-item{display:flex;align-items:flex-start;gap:10px;padding:7px 10px;border-radius:8px;color:var(--ink);font-size:.9rem;line-height:1.35}
.nav-item:hover{background:var(--teal-soft);text-decoration:none}
.nav-item.active{background:var(--navy);color:#fff}
.nav-item .ic{width:22px;flex:none;text-align:center;color:var(--teal)}
.nav-item.active .ic{color:#fff}
.nav-item .num{display:inline-grid;place-items:center;width:22px;height:22px;border-radius:50%;border:1.5px solid var(--line);font-size:.75rem;font-weight:700;color:var(--muted)}
.nav-item .num.seen{border-color:var(--teal);color:var(--teal)}
.nav-item .num.done{background:var(--ok);border-color:var(--ok);color:#fff}
.nav-item.active .num{border-color:#fff;color:#fff}
.side-backdrop{display:none}
/* ---------- main ---------- */
.main{padding:calc(var(--top) + 24px) 32px 40px;max-width:1180px}
body.has-side .main{margin-left:var(--side)}
body.no-side .main{margin:0 auto}
.main.wide{max-width:none}
.footer{padding:18px 32px 28px;color:var(--muted);font-size:.8rem;display:flex;flex-wrap:wrap;gap:6px 24px;justify-content:space-between;border-top:1px solid var(--line)}
body.has-side .footer{margin-left:var(--side)}
/* ---------- components ---------- */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:20px 22px;box-shadow:var(--shadow);margin-bottom:18px}
.card h2:first-child,.card h3:first-child{margin-top:0}
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(2,minmax(0,1fr))}.g3{grid-template-columns:repeat(3,minmax(0,1fr))}.g4{grid-template-columns:repeat(4,minmax(0,1fr))}
.btn{display:inline-flex;align-items:center;gap:6px;border:1px solid transparent;border-radius:9px;padding:9px 16px;font:inherit;font-weight:600;cursor:pointer;line-height:1.2;text-decoration:none!important;transition:.15s}
.btn.sm{padding:6px 11px;font-size:.84rem}
.btn-primary{background:var(--teal);color:#fff}.btn-primary:hover{background:#0b6870}
.btn-navy{background:var(--navy);color:#fff}.btn-navy:hover{background:var(--navy-2)}
.btn-gold{background:var(--gold);color:#fff}
.btn-ghost{background:transparent;border-color:rgba(255,255,255,.4);color:#fff}
.btn-light{background:#fff;border-color:var(--line);color:var(--ink)}.btn-light:hover{border-color:var(--teal);color:var(--teal)}
.btn-danger{background:var(--bad);color:#fff}
.btn:disabled{opacity:.55;cursor:not-allowed}
.alert{padding:12px 16px;border-radius:10px;margin-bottom:16px;border:1px solid}
.alert-ok{background:var(--ok-soft);border-color:#b7e1c8;color:#14532d}
.alert-err{background:var(--bad-soft);border-color:#f3c3bf;color:#7f1d1d}
.alert-warn{background:var(--warn-soft);border-color:#f2dc9b;color:#6b4b00}
.alert-info{background:var(--teal-soft);border-color:#b5dfe2;color:#0b4b51}
.badge{display:inline-block;padding:2px 9px;border-radius:999px;font-size:.75rem;font-weight:700;background:var(--teal-soft);color:var(--teal);white-space:nowrap}
.badge.gold{background:var(--gold-soft);color:var(--gold)}.badge.navy{background:#e6ebf5;color:var(--navy)}
.badge.ok{background:var(--ok-soft);color:var(--ok)}.badge.bad{background:var(--bad-soft);color:var(--bad)}.badge.warn{background:var(--warn-soft);color:var(--warn)}
.muted{color:var(--muted)} .right{text-align:right} .center{text-align:center} .nowrap{white-space:nowrap}
.stat{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;box-shadow:var(--shadow)}
.stat .v{font-size:1.7rem;font-weight:800;color:var(--navy);line-height:1.1}
.stat .l{font-size:.82rem;color:var(--muted)}
.bar{height:8px;background:#e8ecf2;border-radius:99px;overflow:hidden}
.bar>i{display:block;height:100%;background:linear-gradient(90deg,var(--teal),#19a3a6);border-radius:99px}
/* forms */
label{font-weight:600;font-size:.88rem;display:block;margin:10px 0 4px}
input[type=text],input[type=password],input[type=email],input[type=url],input[type=number],input[type=date],select,textarea{width:100%;padding:9px 12px;border:1px solid #cdd3dd;border-radius:9px;font:inherit;background:#fff;color:var(--ink)}
input:focus,select:focus,textarea:focus{outline:2px solid #9fd6da;border-color:var(--teal)}
textarea{min-height:120px;resize:vertical}
.form-row{display:flex;gap:12px;flex-wrap:wrap;align-items:flex-end}.form-row>*{flex:1;min-width:160px}
/* tables */
.table-wrap{overflow-x:auto;margin:12px 0;-webkit-overflow-scrolling:touch}
table{border-collapse:collapse;width:100%;background:#fff;font-size:.9rem}
th,td{border:1px solid var(--line);padding:7px 10px;vertical-align:top;text-align:left}
th{background:#eef2f8;color:var(--navy);font-weight:700}
table.data tr:hover td{background:#fafbfd}
/* ---------- landing ---------- */
.hero{border-radius:16px;overflow:hidden;box-shadow:var(--shadow);margin-bottom:22px;background:#fff}
.hero img{display:block;width:100%}
.hero-cta{display:flex;flex-wrap:wrap;gap:10px;padding:16px 20px;align-items:center;justify-content:space-between;border-top:1px solid var(--line)}
.part-card{border-top:4px solid var(--teal)}
.part-card.p2{border-top-color:var(--gold)}
.ch-list{list-style:none;padding:0;margin:0}
.ch-list li{display:flex;gap:10px;padding:9px 0;border-bottom:1px dashed var(--line)}
.ch-list li:last-child{border-bottom:0}
.ch-list .n{flex:none;width:30px;height:30px;border-radius:8px;background:var(--navy);color:#fff;display:grid;place-items:center;font-weight:700}
.weights{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.weights div{background:var(--gold-soft);border-radius:10px;padding:14px;text-align:center}
.weights b{display:block;font-size:1.5rem;color:var(--gold)}
/* ---------- lesson content ---------- */
.lesson-head{background:linear-gradient(120deg,var(--navy),#24508f 60%,var(--teal));color:#fff;border-radius:16px;padding:24px 26px;margin-bottom:20px}
.lesson-head h1{color:#fff;margin:.2em 0}
.lesson-head .meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:8px}
.lesson-head .badge{background:rgba(255,255,255,.18);color:#fff}
.toc{font-size:.9rem}
.toc a{display:block;padding:3px 0;color:var(--ink)}
.toc a.l3{padding-left:16px;color:var(--muted);font-size:.86rem}
.lesson{font-family:"Noto Serif",Georgia,serif;font-size:1.02rem;line-height:1.75}
.lesson h2,.lesson h3,.lesson h4,.lesson h5,.lesson h6{font-family:"Be Vietnam Pro",sans-serif;scroll-margin-top:80px}
.lesson h2{border-bottom:2px solid var(--gold);padding-bottom:6px}
.lesson h5,.lesson h6{font-size:.98rem;color:var(--teal)}
.lesson p{margin:.55em 0;text-align:justify}
.lesson img{display:block;margin:12px auto;border-radius:8px;max-height:560px;width:auto}
.lesson table img{max-height:180px;margin:4px auto}
.lesson table{font-family:"Be Vietnam Pro",sans-serif;font-size:.86rem}
.lesson pre{background:#0f1b2d;color:#e6edf7;border-radius:10px;padding:14px 16px;overflow:auto;font-size:.82rem;line-height:1.5;font-family:Consolas,"Courier New",monospace;max-height:520px}
.lesson blockquote{border-left:4px solid var(--teal);margin:10px 0;padding:6px 14px;background:var(--teal-soft);border-radius:0 8px 8px 0}
.lesson math{font-size:1.05em}
.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:22px;align-items:start}
.lesson-side{position:sticky;top:calc(var(--top) + 16px);max-height:calc(100vh - var(--top) - 32px);overflow:auto}
details.kh{border:1px solid var(--line);border-radius:10px;margin:12px 0;background:#fff}
details.kh>summary{cursor:pointer;padding:12px 16px;font-weight:700;color:var(--navy);font-family:"Be Vietnam Pro",sans-serif}
details.kh>div{padding:0 18px 12px}
/* ---------- quiz ---------- */
.quiz-box{border:2px solid var(--teal);border-radius:16px;background:#fff;margin-top:28px;overflow:hidden}
.quiz-box>h2{margin:0;padding:16px 20px;background:var(--teal);color:#fff;font-size:1.15rem}
.qtabs{display:flex;flex-wrap:wrap;gap:6px;padding:12px 16px 0;border-bottom:1px solid var(--line);background:#f7fafb}
.qtab{border:1px solid var(--line);border-bottom:0;background:#fff;padding:9px 14px;border-radius:10px 10px 0 0;cursor:pointer;font:inherit;font-weight:600;color:var(--muted);margin-bottom:-1px}
.qtab.on{color:var(--navy);border-color:var(--teal);border-top-width:3px}
.qtab .sc{font-size:.75rem;margin-left:6px}
.qpane{padding:16px 20px 20px;display:none}.qpane.on{display:block}
.q{border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin:12px 0}
.q .qt{font-weight:600;margin-bottom:8px}
.q .qt b{color:var(--teal);margin-right:4px}
.opt{display:flex;gap:10px;align-items:flex-start;padding:8px 10px;border-radius:8px;cursor:pointer;border:1px solid transparent}
.opt:hover{background:#f3f7f9}
.opt input{margin-top:4px}
.opt.correct{background:var(--ok-soft);border-color:#9fd8b6}
.opt.wrong{background:var(--bad-soft);border-color:#f0b5b0}
.explain{display:none;margin-top:8px;padding:8px 12px;border-radius:8px;background:var(--gold-soft);font-size:.9rem}
.q.graded .explain{display:block}
.tf-row{display:grid;grid-template-columns:32px minmax(0,1fr) auto;gap:10px;align-items:start;border-bottom:1px dashed var(--line);padding:10px 0}
.tf-row .tfb{display:flex;gap:6px}
.tf-row label{margin:0;font-weight:600;display:flex;gap:4px;align-items:center;border:1px solid var(--line);padding:5px 10px;border-radius:8px;cursor:pointer;background:#fff}
.tf-row.ok{background:var(--ok-soft)} .tf-row.no{background:var(--bad-soft)}
.tf-row .explain{grid-column:2/4}
.mt-row{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.4fr);gap:10px;align-items:center;padding:8px 0;border-bottom:1px dashed var(--line)}
.mt-row .k{font-weight:600}
.mt-row.ok select{border-color:var(--ok);background:var(--ok-soft)} .mt-row.no select{border-color:var(--bad);background:var(--bad-soft)}
.mt-row .explain{grid-column:1/3}
.q-actions{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:16px}
.q-result{font-weight:700;color:var(--navy)}
/* CLO levels */
.lv-1{color:var(--bad)}.lv-2{color:var(--warn)}.lv-3{color:var(--teal)}.lv-4{color:var(--ok)}.lv-none{color:var(--muted)}
.clo-card{border-left:5px solid var(--teal)}
/* login */
.auth-wrap{max-width:980px;margin:0 auto;display:grid;grid-template-columns:1.25fr 1fr;gap:22px;align-items:stretch}
.auth-art{border-radius:16px;overflow:hidden;box-shadow:var(--shadow);background:#fff;display:flex;flex-direction:column}
.auth-art img{display:block;width:100%}
.auth-art .info{padding:16px 20px;font-size:.92rem}
.warn-box{border:2px dashed var(--gold);background:var(--gold-soft);border-radius:12px;padding:14px 16px;margin:12px 0}
/* modal */
.modal{position:fixed;inset:0;background:rgba(15,25,45,.55);display:none;align-items:center;justify-content:center;z-index:100;padding:16px}
.modal.on{display:flex}
.modal .box{background:#fff;border-radius:16px;max-width:520px;width:100%;padding:22px 24px;box-shadow:0 20px 60px rgba(0,0,0,.3)}
.modal .box h3{margin-top:0;color:var(--bad)}
.cred{font-family:Consolas,monospace;background:#0f1b2d;color:#fff;padding:10px 14px;border-radius:8px;margin:8px 0;font-size:1rem}
/* flipbook */
.flip-wrap{background:#2b3442;border-radius:16px;padding:20px;display:flex;flex-direction:column;align-items:center}
.flip-ctrl{display:flex;gap:10px;align-items:center;color:#fff;margin-top:12px;flex-wrap:wrap;justify-content:center}
/* responsive */
@media (max-width:1100px){.lesson-layout{grid-template-columns:1fr}.lesson-side{position:static;max-height:none}}
@media (max-width:900px){
  .menu-btn{display:block}
  .sidebar{transform:translateX(-100%);transition:transform .2s;box-shadow:0 0 30px rgba(0,0,0,.2)}
  body.side-open .sidebar{transform:none}
  body.side-open .side-backdrop{display:block;position:fixed;inset:var(--top) 0 0 0;background:rgba(0,0,0,.3);z-index:25}
  body.has-side .main,body.has-side .footer{margin-left:0}
  .main{padding:calc(var(--top) + 16px) 16px 32px}
  .g2,.g3,.g4{grid-template-columns:1fr}
  .auth-wrap{grid-template-columns:1fr}
  .who,.brand small{display:none}
  .weights{grid-template-columns:1fr}
}
@media (max-width:600px){.top-right .btn-ghost{display:none}.brand b{font-size:.85rem}.tf-row{grid-template-columns:24px 1fr}.tf-row .tfb{grid-column:2}.mt-row{grid-template-columns:1fr}}
@media print{.topbar,.sidebar,.footer,.quiz-box,.lesson-side{display:none}body.has-side .main{margin:0;padding:0}}
.lesson-layout>*{min-width:0}
.lesson-head .badge{white-space:normal}
.lesson{overflow-wrap:anywhere}
.lesson table{min-width:0}

/* TKNC */
.lesson .note-box{background:#f4f7fb;border-left:4px solid var(--navy);}
.lesson h3.act{margin-top:26px;padding:8px 12px;background:#fbf6e9;border-left:4px solid var(--gold);border-radius:6px;font-size:1.05em}
.lesson h3.act .badge{margin-right:6px}
.lesson p.cap{margin:14px 0 6px;color:var(--navy);font-size:.95em}
.lesson math[display=block]{display:block;margin:12px auto;overflow-x:auto;font-size:1.1em}
.lesson img{max-width:100%;height:auto}
/* AI */
.ai-box{margin:10px 0 12px;padding:10px 12px;border:1px dashed var(--gold);border-radius:10px;background:#fffdf6}
.ai-box textarea.ai-text{width:100%;margin:6px 0}
.ai-card{margin-top:10px;font-size:.92rem}
.ai-card .ai-head{font-weight:700;color:var(--gold);margin-bottom:4px}
.ai-card p{margin:.35em 0}