/* ==========================================================================
   OCEAN LUXE cho Ôn thi CF2102 (19/10/2026) – cùng ngôn ngữ thiết kế với web ECR301:
   nền xanh nước biển, mực navy, đường kẻ vàng champagne, tiêu đề serif Playfair Display, chữ Be Vietnam Pro.
   File này nạp SAU khối <style> trong index.html nên ghi đè; mọi màu lấy từ token ở :root (index.html).
   ========================================================================== */
html{scroll-padding-top:150px}
body{font-size:var(--fs);line-height:1.65;-webkit-font-smoothing:antialiased;
  background:
    radial-gradient(1100px 520px at 90% -8%,color-mix(in srgb,var(--sky) 26%,transparent),transparent 62%),
    radial-gradient(900px 560px at -8% 4%,color-mix(in srgb,var(--aqua) 14%,transparent),transparent 62%),
    var(--bg);background-attachment:fixed}
::selection{background:color-mix(in srgb,var(--brand) 28%,transparent)}
:focus-visible{outline:3px solid color-mix(in srgb,var(--brand) 60%,transparent);outline-offset:2px}
.container{max-width:1180px}
h1,h2,h3{letter-spacing:-.005em}
.section-title,.page-h,.lesson-h,.chead h1,.hero h1,.card h2,.cta h2,.fm-cn,.today-h{font-family:var(--display)}
.section-title{font-weight:700;font-size:clamp(23px,3vw,30px);line-height:1.2;margin:40px 0 14px;color:var(--ink);display:flex;align-items:center;gap:16px}
.section-title:after{content:"";height:1px;flex:1;min-width:24px;background:linear-gradient(90deg,var(--gold),transparent)}
.section-title.tight{margin:0}.section-title.tight:after{display:none}
.card h2{font-size:21px}
.muted{color:var(--muted)}

/* ---------- khung đầu trang ---------- */
.topbar{background:color-mix(in srgb,var(--card) 88%,transparent);-webkit-backdrop-filter:saturate(1.4) blur(12px);backdrop-filter:saturate(1.4) blur(12px);border-bottom:0;box-shadow:0 1px 0 var(--line),0 10px 28px rgba(90,50,10,.07)}
.logo{font-family:var(--display);font-size:25px;letter-spacing:-.01em;color:var(--ink);display:inline-block}
.logo:before{content:"";display:inline-block;vertical-align:-7px;margin-right:9px;width:30px;height:30px;border-radius:9px;background:url(icon.svg) center/cover no-repeat;box-shadow:0 4px 10px rgba(60,30,5,.25)}
.logo span{color:var(--gold)}
.search input{background-color:color-mix(in srgb,var(--sunk) 55%,var(--card));border-color:var(--line);border-radius:14px}
.search input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 25%,transparent)}
.sugg{border-radius:16px}
.top-links a{border-radius:11px;transition:background .15s,color .15s}
.top-links a:hover{background:var(--brand-soft);color:var(--brand-dark)}
.top-links .btn{color:#fff!important}
.ib{border-radius:11px;background:var(--card);border-color:var(--line)}
.ib:hover{border-color:var(--gold)}
.seg{background:var(--sunk);border:1px solid var(--line)}
.seg button[aria-pressed="true"]{background:linear-gradient(180deg,color-mix(in srgb,var(--brand) 80%,#fff),var(--brand));color:#fff;box-shadow:0 4px 10px color-mix(in srgb,var(--brand) 28%,transparent)}
.gradebar{background:linear-gradient(125deg,var(--sea-a),#8A3E0C 70%,#B5601F);box-shadow:inset 0 -1px 0 color-mix(in srgb,var(--hero-gold) 45%,transparent)}
:root[data-theme="dark"] .gradebar{background:linear-gradient(125deg,#1E1006,#3A200C 70%,#5A3312)}
.grades>li>button{font-family:var(--ui);letter-spacing:.02em}
.grades>li:hover>button,.grades>li.open>button{background:rgba(255,255,255,.14)}
.mega{border-radius:0 0 22px 22px;box-shadow:0 22px 50px rgba(60,30,5,.28)}
.mega h4{color:var(--brand-dark)}
.tabs{background:color-mix(in srgb,var(--card) 90%,transparent);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.tabs .container{padding-top:8px;padding-bottom:8px}
.tabs a{border-radius:12px;padding:9px 15px;transition:background .15s,color .15s}
.tabs a:hover{background:var(--brand-soft);color:var(--brand-dark)}
.tabs a.active{background:linear-gradient(180deg,color-mix(in srgb,var(--brand) 80%,#fff),var(--brand));color:#fff;box-shadow:0 8px 18px color-mix(in srgb,var(--brand) 30%,transparent)}
.tabs a.globe-tab{color:#5a3b00;background:linear-gradient(180deg,#F8DE9A,#E3B94C);box-shadow:0 6px 14px rgba(200,162,74,.35)}
.tabs a.globe-tab:hover,.tabs a.globe-tab.active{filter:brightness(1.05);color:#3b2700;background:linear-gradient(180deg,#FBE7B2,#E8C25A)}
.promo{border-radius:16px;border-left-width:5px;border-left-color:var(--gold);background:linear-gradient(90deg,var(--gold-s),var(--card))}
.promo b{color:var(--gold-d)}

/* ---------- thẻ, nút, chip ---------- */
.card,.bu-q,.qcard,.ccard,.fm,.term,.chap,.acc,.rvq,.chart,.dlg-box{border-radius:20px;border-color:var(--line)}
.card,.bu-q,.ccard{box-shadow:var(--shadow)}
.btn{border-radius:13px;padding:11px 19px;font-size:14.5px;letter-spacing:.005em;
  background:linear-gradient(180deg,color-mix(in srgb,var(--brand) 80%,#fff),var(--brand));border-color:transparent;
  box-shadow:0 8px 18px color-mix(in srgb,var(--brand) 26%,transparent),inset 0 1px 0 rgba(255,255,255,.28);transition:transform .15s,box-shadow .15s}
.btn:hover{background:linear-gradient(180deg,var(--brand),var(--brand-dark));transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn.sm{padding:7px 13px;font-size:13.5px;border-radius:11px}
.btn.sec{background:var(--card);color:var(--brand-dark)!important;border:1px solid var(--line);box-shadow:none}
.btn.sec:hover{background:var(--brand-soft);border-color:var(--brand)}
.btn[disabled]{box-shadow:none}
.badge{background:var(--gold-s);color:var(--gold-d)}
.pill{background:var(--card);border:1px solid var(--line)}
.pill.vip{background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#4a3200;border-color:transparent}
.pill.vip:hover{color:#2b1c00!important;filter:brightness(1.05);background:linear-gradient(180deg,#FBE7B2,#E8C25A)}
.chips span{background:var(--sunk);border:1px solid var(--line)}
.grade-chips a{border-radius:999px}
.grade-chips a:hover,.grade-chips a.on{background:var(--brand-soft);color:var(--brand-dark);border-color:var(--brand)}
select,input[type=search],input[type=number],.toolbar input,.fm-in{border-radius:12px;border-color:var(--line);background:var(--card)}
select:focus,input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 25%,transparent)}
.bar{height:9px;background:var(--sunk)}
.bar i{background:linear-gradient(90deg,var(--c,var(--brand)),color-mix(in srgb,var(--c,var(--brand)) 45%,var(--sky)))}
.crumb{font-size:13.5px}
.tabs2{border-bottom:0;gap:6px;padding:7px;background:var(--card);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow);margin-bottom:18px}
.tabs2 a{border:0;margin:0;border-radius:12px;padding:9px 16px}
.tabs2 a:hover{background:var(--brand-soft);color:var(--brand-dark)}
.tabs2 a.on{background:linear-gradient(180deg,color-mix(in srgb,var(--c,var(--brand)) 78%,#fff),var(--c,var(--brand)));color:#fff;box-shadow:0 8px 18px color-mix(in srgb,var(--c,var(--brand)) 30%,transparent)}

/* ---------- hero (trang chủ, ngành) ---------- */
.hero{position:relative;overflow:hidden;border:0;border-radius:30px;padding:44px 44px 84px;text-align:left;color:#fff;
  background:linear-gradient(125deg,var(--sea-a) 0%,var(--sea-b) 66%,color-mix(in srgb,var(--sea-b) 62%,var(--sky)) 135%);
  box-shadow:var(--shadow-lg),inset 0 0 0 1px rgba(255,255,255,.10),inset 0 1px 0 rgba(255,255,255,.24)}
.hero:before{content:"";position:absolute;left:0;right:0;bottom:0;height:64px;background:var(--wave) center bottom/100% 100% no-repeat;pointer-events:none}
.hero:after{content:"";position:absolute;width:320px;height:320px;right:-90px;top:-130px;border-radius:50%;border:1px solid color-mix(in srgb,var(--hero-gold) 40%,transparent);box-shadow:0 0 0 26px rgba(255,255,255,.035),0 0 0 27px color-mix(in srgb,var(--hero-gold) 18%,transparent);pointer-events:none}
.hero>*{position:relative;z-index:1}
.hero .brand{color:var(--hero-gold);font-size:12px;font-weight:700;letter-spacing:.2em;display:flex;align-items:center;gap:12px;text-transform:uppercase}
.hero .brand:before{content:"";width:34px;height:1px;background:var(--hero-gold)}
.hero h1{font-weight:700;font-size:clamp(29px,4.8vw,46px);line-height:1.12;margin:12px 0 14px;letter-spacing:-.01em;color:#fff}
.hero h1 em{font-style:italic;font-weight:600;color:var(--hero-gold)}
.hero>p,.hero-in>p{color:rgba(255,255,255,.92);font-size:16px;max-width:64ch;margin:0 0 20px}
.hero-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(220px,.85fr);gap:28px;align-items:center}
.hero-in{min-width:0}
.hero-globe{display:block;width:100%;max-width:400px;aspect-ratio:1;margin:0 auto;filter:drop-shadow(0 18px 38px rgba(0,0,0,.35))}
.hero-search{max-width:560px;margin:0 0 18px}
.hero-search input{background:#fff;color:#0B2542;border:0;border-radius:15px;padding:14px 18px;box-shadow:0 10px 24px rgba(0,0,0,.20)}
.hero-search input::placeholder{color:#8A7058}
.hero-search .btn{border-radius:15px;background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#3b2700!important;box-shadow:0 10px 24px rgba(0,0,0,.2)}
.hero .grade-chips{justify-content:flex-start}
.hero .grade-chips a{background:rgba(255,255,255,.12);border-color:rgba(255,255,255,.28);color:#fff}
.hero .grade-chips a:hover,.hero .grade-chips a.on{background:#fff;color:#084A92;border-color:#fff}
.stats{justify-content:flex-start;margin-top:18px}
.stats span{padding:7px 14px;border-radius:999px;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.18);color:#fff;font-size:13px}
.stats span b{color:var(--hero-gold)}
.hero .btn.gold,.btn.gold{background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#3b2700!important;box-shadow:0 10px 24px rgba(0,0,0,.2)}
.hero .acts{margin-top:4px}

/* ---------- thẻ môn học ---------- */
.ccard{position:relative;overflow:hidden;border-top:0;padding:0;gap:0;transition:transform .15s,box-shadow .15s}
.ccard:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg)}
.ccard>*{margin-left:20px;margin-right:20px}
.ccard .code{margin:0;padding:16px 20px;display:block;color:#fff;font:800 13px/1 var(--ui);letter-spacing:.16em;
  background:linear-gradient(120deg,color-mix(in srgb,var(--c) 40%,#2E1A0B),var(--c));position:relative;margin-left:0;margin-right:0}
.ccard .code:after{content:"";position:absolute;left:0;right:0;bottom:0;height:22px;background:var(--wave) center bottom/100% 100% no-repeat}
.ccard h3{margin-top:14px;font-family:var(--display);font-size:22px;line-height:1.25}
.ccard h3 a:hover{color:var(--brand)}
.ccard .en{margin-top:2px;margin-bottom:6px}
.ccard .bar{margin-top:8px}
.ccard small.muted{margin-top:4px}
.ccard .note{margin-top:8px}
.ccard .chips{margin-top:6px}
.ccard .links{padding:10px 0 20px}
.ccard .links a{border-radius:999px}
.ccard .links a:hover{background:var(--brand-soft)}
.ccard .links a.glink{background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#3b2700;border-color:transparent}

/* ---------- đầu trang môn ---------- */
.chead{position:relative;overflow:hidden;border:0;border-radius:28px;padding:30px 34px 52px;color:#fff;
  background:linear-gradient(125deg,color-mix(in srgb,var(--c) 38%,#2E1A0B) 0%,var(--c) 85%,color-mix(in srgb,var(--c) 60%,var(--sky)) 150%);
  box-shadow:var(--shadow-lg),inset 0 0 0 1px rgba(255,255,255,.10),inset 0 1px 0 rgba(255,255,255,.22)}
.chead:before{content:"";position:absolute;left:0;right:0;bottom:0;height:46px;background:var(--wave) center bottom/100% 100% no-repeat;pointer-events:none}
.chead:after{content:"";position:absolute;width:260px;height:260px;right:-70px;top:-110px;border-radius:50%;border:1px solid color-mix(in srgb,var(--hero-gold) 40%,transparent);box-shadow:0 0 0 22px rgba(255,255,255,.035);pointer-events:none}
.chead>*{position:relative;z-index:1}
.chead .code{color:var(--hero-gold);font:800 12.5px var(--ui);letter-spacing:.2em;display:flex;align-items:center;gap:12px}
.chead .code:before{content:"";width:30px;height:1px;background:var(--hero-gold)}
.chead h1{font-weight:700;font-size:clamp(25px,3.8vw,38px);color:#fff;margin:8px 0 4px}
.chead .en{color:rgba(255,255,255,.88)}
.chead .chips span{background:rgba(255,255,255,.14);border-color:rgba(255,255,255,.2);color:#fff}
.chead .note{background:rgba(255,255,255,.16);color:#fff}
.chead .sched{color:rgba(255,255,255,.9)}
.chead .sched a{color:var(--hero-gold)}

/* ---------- danh sách chương, bài học ---------- */
.chap{padding:14px 18px;transition:transform .12s,border-color .12s,box-shadow .12s;box-shadow:var(--shadow)}
.chap:hover{transform:translateX(3px);border-color:var(--brand)}
.chap .no{background:linear-gradient(135deg,var(--sea-a),var(--sea-b));color:#fff;font-family:var(--display);font-size:17px;box-shadow:0 6px 14px rgba(138,62,12,.3)}
.chap .t{font-size:16.5px}
.side{border-radius:22px}
.side li.cur a{background:linear-gradient(90deg,var(--brand-soft),transparent);color:var(--brand-dark)}
.side .n{background:var(--sunk)}
.side li.cur .n{background:var(--brand);color:#fff}
.lesson-h{font-weight:700;font-size:clamp(25px,3.6vw,36px);line-height:1.2}
.toc{background:linear-gradient(135deg,var(--brand-soft),var(--card));border:1px solid var(--line)}
.sec h2{font-family:var(--display);font-size:clamp(20px,2.6vw,26px);display:block;padding-left:16px;border-left:6px solid var(--sea-b);border-image:linear-gradient(180deg,var(--sea-c),var(--sea-b)) 1;line-height:1.25}
.term{padding:13px 18px;box-shadow:0 4px 14px rgba(90,50,10,.05);transition:border-color .12s,transform .12s}
.term:hover{border-color:var(--brand);transform:translateX(2px)}
.term dt{color:var(--brand-dark);font-size:1.02em}
.term dd{line-height:1.7}
.sp.big,.sp:hover{background:var(--brand-soft)}
.chart{box-shadow:var(--shadow);background:var(--card)}
.outline summary,.fm-gen summary{color:var(--brand-dark)}
.cta{background:linear-gradient(135deg,var(--brand-soft),var(--card))}

/* ---------- trang chủ: giờ học, dịch vụ ---------- */
.live{position:relative;overflow:hidden;border-radius:24px;background:linear-gradient(125deg,var(--sea-a),var(--sea-b));box-shadow:var(--shadow-lg),inset 0 1px 0 rgba(255,255,255,.2)}
:root[data-theme="dark"] .live{background:linear-gradient(125deg,#1E1006,#3A200C)}
.live:before{content:"";position:absolute;left:0;right:0;bottom:0;height:40px;background:var(--wave) center bottom/100% 100% no-repeat;pointer-events:none}
.live>*{position:relative}
.clock{font-family:var(--display);font-weight:700}
.meter i{background:linear-gradient(90deg,#F8DE9A,#E3B94C)}
.go{background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#3b2700!important}
.datebox{border-radius:22px;background:linear-gradient(160deg,var(--sea-a),var(--sea-b));color:#fff;box-shadow:var(--shadow-lg);width:92px}
.datebox b{color:#fff;font-family:var(--display)}
.today-list a{border-radius:16px;box-shadow:0 4px 14px rgba(90,50,10,.05)}
.services .card,.recent .card{transition:transform .15s,box-shadow .15s,border-color .15s}
.services .card:hover,.recent .card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--brand)}
.services .card .ico{width:56px;height:56px;border-radius:17px;display:grid;place-items:center;font-size:28px;margin-bottom:10px;
  background:linear-gradient(135deg,var(--brand-soft),color-mix(in srgb,var(--sky) 34%,var(--card)));border:1px solid color-mix(in srgb,var(--brand) 20%,var(--line))}
.services .card h3{font-family:var(--display);font-size:20px}
.services .card.glow{background:linear-gradient(135deg,var(--gold-s),var(--card));border-color:color-mix(in srgb,var(--gold) 55%,var(--line))}
.services .card.glow .ico{background:linear-gradient(135deg,#F8DE9A,#E3B94C)}
.acc>button{font-family:var(--display);font-size:18px}

/* ---------- bảng thuật ngữ, thời khoá biểu ---------- */
table.dt{border-radius:20px;box-shadow:var(--shadow)}
.dt th{background:linear-gradient(180deg,var(--sea-b),var(--sea-a));color:#fff}
.tt-wrap{border-radius:22px}
.tt thead th{background:linear-gradient(180deg,var(--sea-b),var(--sea-a));color:#fff}
.tt thead th small{color:rgba(255,255,255,.85)}
.tt th.slot{background:var(--sunk)}
a.cls{border-radius:14px}

/* ---------- trắc nghiệm: câu hỏi to, rõ ---------- */
.qcard{position:relative;overflow:hidden;padding:clamp(18px,3vw,30px)}
.qcard:before{content:"";position:absolute;left:0;right:0;top:0;height:6px;background:linear-gradient(90deg,var(--brand),color-mix(in srgb,var(--brand) 35%,var(--sky)))}
.qno{background:var(--accent-soft);color:var(--gold-d);font-family:var(--display);font-size:15px}
.qtext{font-size:clamp(19px,2.4vw,24px);line-height:1.55;font-weight:600;color:var(--ink);padding:16px 20px;background:var(--sunk);border-radius:16px;border-left:6px solid var(--brand);margin:6px 0 18px}
.ins{color:var(--gold-d)}
.opts{gap:11px}
.opt{font-size:clamp(16.5px,2vw,19px);line-height:1.5;padding:13px 16px;border-width:2px;border-radius:15px;gap:14px;align-items:center;transition:border-color .12s,background .12s,transform .12s}
.opt:hover:not(:disabled){transform:translateX(3px);border-color:var(--brand);background:var(--brand-soft)}
.opt .L{width:36px;height:36px;border-radius:11px;font-size:15px;font-weight:700;background:var(--sunk);color:var(--brand-dark)}
.opt.sel{box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 22%,transparent)}
.expl{border-radius:16px;border-left:6px solid var(--brand);font-size:16.5px;line-height:1.75}
.expl.ok{border-left-color:var(--good)}.expl.no{border-left-color:var(--bad)}
.run-top{border-radius:20px}
.timer{font-family:var(--display);font-size:22px;background:var(--sunk)}
.pal .grid button{border-radius:11px;font-weight:700}
.pal .grid button.cur{outline:3px solid color-mix(in srgb,var(--brand) 60%,transparent)}
.score{border-width:9px;font-family:var(--display)}
.rvq{box-shadow:var(--shadow)}
.fc{border-radius:24px;border-color:var(--gold);box-shadow:var(--shadow)}
.fc .big{font-family:var(--display)}

/* ---------- Đề quan trọng, công thức ---------- */
.bu-course{border-top:0;position:relative;overflow:hidden;padding-top:22px}
.bu-course:before{content:"";position:absolute;left:0;right:0;top:0;height:7px;background:linear-gradient(90deg,var(--c,var(--brand)),color-mix(in srgb,var(--c,var(--brand)) 40%,var(--sky)))}
.bu-q{transition:border-color .12s}
.bu-q:hover{border-color:var(--brand)}
.fm{box-shadow:0 4px 14px rgba(90,50,10,.05)}
.fm-big{background:linear-gradient(135deg,var(--brand-soft),var(--card));border:1px solid var(--line);border-radius:16px}
.fm-cn{border-bottom:0;position:relative;padding-bottom:10px}
.fm-cn:after{content:"";position:absolute;left:0;right:0;bottom:0;height:2px;background:linear-gradient(90deg,var(--c,var(--gold)),transparent)}
.fm-calc{border-radius:16px;border:1px solid var(--line)}

/* ---------- chân trang, thông báo ---------- */
footer{position:relative;overflow:hidden;margin-top:34px;padding:42px 0 38px;background:linear-gradient(125deg,var(--sea-a),var(--sea-b));color:#F3E2C8}
:root[data-theme="dark"] footer{background:linear-gradient(125deg,#0D0804,#3A200C)}
footer:before{content:"";position:absolute;left:0;right:0;bottom:0;height:46px;background:var(--wave) center bottom/100% 100% no-repeat;pointer-events:none}
footer .container{position:relative}
footer h5{font-family:var(--display);font-size:20px;color:#fff}
footer .copy{border-top-color:rgba(255,255,255,.2);color:#DCC3A0}
footer a:hover{color:var(--hero-gold)}
.toast{background:linear-gradient(125deg,var(--sea-a),var(--sea-b));border:1px solid color-mix(in srgb,var(--hero-gold) 55%,transparent)}
.dlg-box{border-radius:22px}

/* ---------- điện thoại ---------- */
@media (max-width:900px){
  .hero-grid{grid-template-columns:1fr}
  .hero-globe{max-width:300px}
}
@media (max-width:620px){
  .hero{padding:28px 22px 66px;border-radius:24px}
  .chead{padding:24px 20px 46px;border-radius:22px}
  .qtext{padding:13px 14px;border-left-width:5px}
  .opt .L{width:32px;height:32px}
  .section-title{margin-top:30px}
  .tabs2{overflow-x:auto;flex-wrap:nowrap}
}
@media (prefers-reduced-motion:reduce){.ccard:hover,.chap:hover,.term:hover,.services .card:hover,.btn:hover,.opt:hover{transform:none}}
@media print{.hero:before,.hero:after,.chead:before,.chead:after,footer:before{display:none}.hero,.chead{background:#fff!important;color:#000!important;box-shadow:none}.hero h1,.chead h1{color:#000}}

.search{max-width:340px}
.hero .acts{display:flex;flex-wrap:wrap;gap:10px;align-items:center}

/* ---------- mục lý thuyết bổ sung ---------- */
.bs-tag{display:inline-block;margin-left:12px;vertical-align:middle;font:800 11px/1 var(--ui);letter-spacing:.1em;text-transform:uppercase;padding:5px 10px;border-radius:999px;background:linear-gradient(180deg,#F8DE9A,#E3B94C);color:#3b2700;white-space:nowrap}
.sec.bs .term{border-left:4px solid var(--gold)}
.lesson-h .vi,.chead h1 .vi,.sec h2 .vi,.chap .t .vi,.hero h1 .vi,.today-h .vi{font-family:var(--ui);font-weight:500;font-size:.62em;display:block;color:var(--muted);letter-spacing:0}
.chead h1 .vi{color:rgba(255,255,255,.8)}
.lesson-h .en,.sec h2 .en{display:block}
.hero h1{font-size:clamp(26px,4.2vw,42px)}
/* danh sách Đề quan trọng / xem lại bài: chữ câu hỏi gọn hơn trong lúc làm bài */
.bu-q .qtext,.rvq .qtext,.reslist .qtext{font-size:clamp(16.5px,1.9vw,19px);padding:12px 16px;margin:6px 0 12px;border-left-width:5px}