:root{
  --den:#111214; --den2:#1b1c20; --do:#e3262f; --do-dam:#b3141c; --do-nhat:#fde8e9;
  --chu:#1d1d1f; --chu2:#5b5d63; --vien:#e4e4e8; --nen:#ffffff; --nen2:#f5f5f7; --xanh:#1f7a4c;
  --tieu:'Barlow Condensed',system-ui,sans-serif; --than:'Be Vietnam Pro',system-ui,-apple-system,'Segoe UI',Roboto,Arial,sans-serif;
}
*{box-sizing:border-box}
html,body{margin:0}
body{font-family:var(--than);color:var(--chu);background:var(--nen);font-size:16px;line-height:1.6;display:flex;flex-direction:column;min-height:100vh}
main{flex:1}
a{color:var(--do-dam)}
img{max-width:100%}
.khung{max-width:1140px;margin:0 auto;padding:0 20px}
h1,h2,h3{line-height:1.2}
.tieu{font-family:var(--tieu);font-size:40px;letter-spacing:.01em;margin:36px 0 18px;text-transform:uppercase}

/* đầu trang */
.dau{background:var(--den);position:sticky;top:0;z-index:20;border-bottom:3px solid var(--do)}
.dau-trong{display:flex;align-items:center;justify-content:space-between;height:64px;gap:16px}
.logo{display:flex;align-items:center;gap:10px;text-decoration:none;color:#fff}
.logo-o img{height:34px;display:block}
.logo-chu{font-family:var(--tieu);font-size:22px;letter-spacing:.06em;font-weight:800}
.logo-chu b{color:var(--do)}
nav{display:flex;align-items:center;gap:18px}
nav a,nav .lk{color:#e8e8ea;text-decoration:none;font-size:14.5px;font-weight:500}
nav a:hover{color:#fff}
nav form{margin:0}
.nut-vien{display:inline-block;border:1.5px solid currentColor;padding:7px 16px;border-radius:8px;text-decoration:none;font-weight:600;font-size:14.5px;color:var(--chu)}
nav .nut-vien{color:#fff;border-color:#fff6}
.lk{background:none;border:0;padding:0;cursor:pointer;font:inherit;color:var(--do-dam);text-decoration:underline}
nav .lk{text-decoration:none}

/* nút */
.nut{display:inline-block;background:var(--do);color:#fff;border:0;border-radius:10px;padding:13px 26px;font:600 16px var(--than);text-decoration:none;cursor:pointer;transition:background .15s}
.nut:hover{background:var(--do-dam)}
.nut.xam{background:#8a8b90;cursor:default}
.nut.rong{width:100%}
.nut.da-xong{background:var(--xanh)}
.nho-nut{padding:7px 12px;font-size:13.5px;border-radius:7px}

/* hero trang chủ */
.hero{background:radial-gradient(1200px 400px at 85% -10%,#e3262f33,transparent),var(--den);color:#fff;margin:0 -20px;padding:56px 20px 60px;border-radius:0 0 22px 22px}
.hero .tren,.hero-khoa .tren{font-size:12.5px;letter-spacing:.22em;font-weight:700;color:#ff8a8f}
.hero h1{font-family:var(--tieu);font-size:clamp(38px,6vw,64px);text-transform:uppercase;margin:10px 0 14px;letter-spacing:.01em}
.hero h1 span{color:var(--do)}
.hero p{max-width:620px;color:#c9c9cd;font-size:17px;margin:0}

.hang-loc{display:flex;justify-content:space-between;align-items:center;gap:16px;flex-wrap:wrap}
.tim{display:flex;border:1.5px solid var(--vien);border-radius:10px;overflow:hidden;width:min(320px,100%)}
.tim input{flex:1;border:0;padding:11px 14px;font:inherit;outline:none;min-width:0}
.tim button{border:0;background:none;padding:0 14px;font-size:20px;cursor:pointer}
.tab{display:flex;gap:22px;border-bottom:1px solid var(--vien);margin-bottom:26px;overflow-x:auto}
.tab a{padding:10px 0;text-decoration:none;color:var(--chu2);font-weight:500;white-space:nowrap;border-bottom:2.5px solid transparent}
.tab a.on{color:var(--do-dam);border-color:var(--do)}

/* thẻ khoá */
.luoi{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:24px;margin-bottom:60px}
.luoi-1{display:grid;gap:18px;margin-bottom:60px}
.the{display:flex;flex-direction:column;border:1px solid var(--vien);border-radius:14px;overflow:hidden;text-decoration:none;color:inherit;background:#fff;transition:transform .15s,box-shadow .15s}
.the:hover{transform:translateY(-3px);box-shadow:0 14px 30px #0000001a}
.the-anh{aspect-ratio:16/9;background:#222 center/cover;position:relative}
.the-anh::after{content:'';position:absolute;inset:0;background:linear-gradient(180deg,transparent 45%,#000a)}
.the-ten-anh{position:absolute;left:16px;bottom:12px;z-index:1;color:#fff;font:800 26px/1 var(--tieu);text-transform:uppercase;letter-spacing:.02em}
.nhan{position:absolute;top:12px;left:12px;z-index:1;background:var(--do);color:#fff;font-size:11.5px;font-weight:700;letter-spacing:.08em;padding:4px 9px;border-radius:5px}
.the-than{padding:16px 18px 18px;display:flex;flex-direction:column;flex:1}
.the h3{margin:0 0 4px;font-size:19px}
.phu{font-size:13px;color:var(--chu2)}
.the p{font-size:14.5px;color:#3c3d42;margin:10px 0 14px;flex:1}
.the-gia b{font-size:18px}
.do{color:var(--do-dam);font-weight:600}
.the.ngang{flex-direction:row}
.the.ngang .the-anh{width:min(320px,38%);aspect-ratio:auto;min-height:170px}
.the.ngang .nut{align-self:flex-start;margin-top:12px;padding:10px 20px}
.rong{color:var(--chu2)}

/* trang khoá */
.hero-khoa{background:linear-gradient(90deg,#0e0f11 30%,#0e0f11cc 55%,#0e0f1155),var(--bia) right center/cover,var(--den);color:#fff}
.hk-trong{padding:70px 20px 64px;max-width:1140px}
.hero-khoa h1{font:800 clamp(42px,7vw,76px)/1 var(--tieu);text-transform:uppercase;margin:12px 0 6px;letter-spacing:.01em}
.hk-phu{color:#ff8a8f;font-size:19px;font-weight:600;margin-bottom:14px}
.hero-khoa p{max-width:560px;color:#d4d4d8;font-size:17px;margin:0 0 24px}
.hai-cot{display:grid;grid-template-columns:minmax(0,1fr) 330px;gap:44px;padding-top:40px;padding-bottom:50px}
.noi-dung h2{font-size:23px;margin:34px 0 10px}
.noi-dung h2:first-child{margin-top:0}
.noi-dung ul{padding-left:20px}.noi-dung li{margin:6px 0}
.dong-tieu{display:flex;justify-content:space-between;align-items:baseline}
.dong-tieu .lk{font-size:14px;font-weight:500}
.hop-app{background:var(--do-nhat);border-left:4px solid var(--do);border-radius:10px;padding:14px 18px;margin:26px 0}
.hop-app p{margin:4px 0 0}
details.phan{border:1px solid var(--vien);border-radius:10px;margin:10px 0;overflow:hidden}
details.phan summary{display:flex;justify-content:space-between;padding:14px 18px;cursor:pointer;background:var(--nen2);list-style:none}
details.phan summary::-webkit-details-marker{display:none}
details.phan summary span{color:var(--chu2);font-size:14px}
.dong-bai{display:flex;align-items:center;gap:12px;padding:11px 18px;border-top:1px solid var(--vien);font-size:15px}
.dong-bai a{color:inherit;text-decoration:none;font-weight:500}.dong-bai a:hover{color:var(--do-dam)}
.dong-bai .ico{width:22px;height:22px;border-radius:50%;background:var(--den);color:#fff;font-size:10px;display:grid;place-items:center;flex:none}
.dong-bai.tai_lieu .ico{background:var(--xanh)}
.dong-bai.sap_co{color:#9a9ba0}.dong-bai.sap_co .ico{background:#d4d4d8}
.dong-bai .tg{margin-left:auto;color:var(--chu2);font-size:13px;white-space:nowrap}
.thu{font-style:normal;font-size:11.5px;font-weight:700;color:var(--xanh);border:1px solid var(--xanh);border-radius:5px;padding:1px 6px}
.gv{display:flex;gap:18px;align-items:flex-start}
.gv img{width:120px;height:120px;object-fit:cover;border-radius:12px;flex:none}
.gv b{font-size:18px;display:block}.gv span{color:var(--chu2);font-size:14px}.gv p{margin:8px 0 0}
.ben{position:relative}
.hop-gia{position:sticky;top:90px;border:1px solid var(--vien);border-radius:14px;padding:22px;box-shadow:0 10px 30px #0000000f}
.gia-to{font:800 38px var(--tieu);color:var(--do-dam);margin:6px 0 10px}
.hop-gia ul{padding-left:18px;margin:0 0 18px;font-size:14.5px;color:#3c3d42}
.hop-gia .nut{width:100%;text-align:center}
.cuoi-cta{background:var(--den);color:#fff;text-align:center;padding:48px 0}
.cuoi-cta h2{font:800 34px var(--tieu);text-transform:uppercase;margin:0 0 20px}

/* tài khoản, mua */
.hop-tk,.hop-mua{max-width:440px;margin:50px auto 70px;border:1px solid var(--vien);border-radius:16px;padding:30px}
.hop-mua{max-width:560px}
.hop-tk h1,.hop-mua h1{margin:0 0 20px;font-size:26px}
label{display:block;font-size:14px;font-weight:600;margin-bottom:14px}
label input{display:block;width:100%;margin-top:6px;padding:12px 14px;border:1.5px solid var(--vien);border-radius:10px;font:16px var(--than)}
label input:focus{outline:none;border-color:var(--do)}
.loi{background:var(--do-nhat);color:var(--do-dam);border-radius:8px;padding:10px 14px;margin-bottom:14px;font-size:14.5px}
.canh{background:#fff4e5;border:1px solid #f0c27a;border-radius:10px;padding:12px 16px;margin:14px 0;font-size:14.5px}
.nho{font-size:13.5px;color:var(--chu2)}
.doi{text-align:center;font-size:14.5px;margin:18px 0 0}
.buoc{display:flex;gap:14px;margin:16px 0}
.buoc .so{width:30px;height:30px;border-radius:50%;background:var(--do);color:#fff;display:grid;place-items:center;font-weight:700;flex:none}
.ma{font-family:ui-monospace,monospace;background:var(--nen2);padding:2px 8px;border-radius:5px;color:var(--do-dam)}
.qr{display:flex;gap:16px;align-items:center;background:var(--nen2);border-radius:12px;padding:14px;margin:6px 0 6px 44px}
.qr img{width:170px;border-radius:8px;background:#fff}

/* phòng học */
.phong{display:grid;grid-template-columns:330px minmax(0,1fr);min-height:calc(100vh - 67px)}
.muc-luc{background:var(--den2);color:#ddd;padding:18px 0;overflow-y:auto;max-height:calc(100vh - 67px);position:sticky;top:67px}
.mt-ve{display:block;color:#fff;text-decoration:none;font-weight:600;padding:0 20px 12px}
.tien-do{padding:0 20px 14px;font-size:13px;color:#aaa;border-bottom:1px solid #ffffff14}
.td-thanh{height:6px;background:#ffffff22;border-radius:9px;overflow:hidden;margin:6px 0}
.the .td-thanh{background:var(--nen2)}
.td-thanh span{display:block;height:100%;background:var(--do);border-radius:9px}
.tien-do b{color:#fff}
.mt-phan{font-size:12px;letter-spacing:.1em;text-transform:uppercase;color:#ff8a8f;font-weight:700;padding:16px 20px 6px}
.mt-bai{display:flex;gap:10px;padding:9px 20px;color:#ddd;text-decoration:none;font-size:14px;line-height:1.4}
a.mt-bai:hover{background:#ffffff0d}
.mt-bai.dang{background:#e3262f22;box-shadow:inset 3px 0 var(--do);color:#fff}
.mt-bai.khoa{color:#77787d}
.mt-bai i{font-style:normal;width:16px;flex:none;color:#9a9ba0}
.mt-bai em{font-style:normal;font-size:11px;color:#77787d}
.man{background:#0b0b0c;color:#fff}
.khung-vd{background:#000;aspect-ratio:16/9;max-height:72vh;display:grid;place-items:center}
.khung-vd video{width:100%;height:100%;background:#000}
.tai-lieu{display:flex;gap:22px;align-items:center;padding:30px;max-width:640px}
.tl-ico{width:90px;height:110px;border-radius:10px;background:var(--xanh);display:grid;place-items:center;font:800 26px var(--tieu);flex:none}
.tai-lieu h2{margin:0 0 6px}.tai-lieu p{color:#bbb;margin:0 0 16px}
.duoi-vd{padding:22px 30px 40px;max-width:900px}
.duoi-vd h1{font-size:24px;margin:0 0 16px}
.man .canh{color:var(--chu)}
.dieu-huong{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}
.man .nut-vien{color:#fff;border-color:#ffffff55}

/* quản trị */
.so-lieu{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:14px;margin-bottom:26px}
.so-lieu div{background:var(--den);color:#fff;border-radius:14px;padding:18px 20px;border-bottom:4px solid var(--do)}
.so-lieu span{font-size:13px;color:#bbb}.so-lieu b{display:block;font:800 36px var(--tieu)}
.bang-cuon{overflow-x:auto;margin-bottom:40px}
.bang{width:100%;border-collapse:collapse;font-size:14.5px}
.bang th{background:var(--nen2);text-align:left;padding:10px 12px;font-size:13px}
.bang td{border-bottom:1px solid var(--vien);padding:10px 12px;vertical-align:middle}
.bang small{color:var(--chu2)}
.bang form{margin:0;white-space:nowrap}
.nhan-cho{background:#fff4e5;color:#9a5b00;padding:3px 9px;border-radius:5px;font-size:12.5px;font-weight:600}
.nhan-ok{background:#e3f3ea;color:var(--xanh);padding:3px 9px;border-radius:5px;font-size:12.5px;font-weight:600}

.van-ban{max-width:760px;margin:40px auto 70px}
.van-ban h1{font-size:32px}.van-ban h2{font-size:19px;margin-top:26px}

.chan{background:var(--den);color:#aaa;font-size:14px;margin-top:auto}
.chan-trong{display:flex;justify-content:space-between;gap:16px;padding-top:26px;padding-bottom:26px;flex-wrap:wrap}
.chan b{color:#fff}.chan a{color:#ccc}

@media (max-width:900px){
  .hai-cot{grid-template-columns:1fr}
  .hop-gia{position:static}
  .phong{grid-template-columns:1fr}
  .muc-luc{position:static;max-height:none;order:2}
  .hero-khoa{background:linear-gradient(180deg,#0e0f11cc,#0e0f11),var(--bia) center/cover}
}
@media (max-width:600px){
  .khung{padding:0 16px}
  .hero{margin:0 -16px;padding:40px 16px 44px}
  nav{gap:12px}nav a,nav .lk{font-size:13.5px;white-space:nowrap}
  .logo-chu{font-size:17px}.logo-o img{height:26px}.logo{gap:7px}
  nav > a:first-child{display:none}
  .the.ngang{flex-direction:column}.the.ngang .the-anh{width:100%;aspect-ratio:16/9;min-height:0}
  .hop-tk,.hop-mua{margin:24px 0 50px;padding:22px 18px;border:0}
  .qr{margin-left:0;flex-direction:column;align-items:flex-start}
  .duoi-vd{padding:18px 16px 30px}
  .gv{flex-direction:column}
}
label select{display:block;width:100%;margin-top:6px;padding:12px 14px;border:1.5px solid var(--vien);border-radius:10px;font:16px var(--than);background:#fff}
label select:focus{outline:none;border-color:var(--do)}
.hai-o{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.hop-tk > .nho{margin:-10px 0 16px}
.the-anh.co-bia::after{display:none}
details.hoi{border-bottom:1px solid var(--vien);padding:4px 0}
details.hoi summary{cursor:pointer;font-weight:600;padding:12px 28px 12px 0;list-style:none;position:relative}
details.hoi summary::-webkit-details-marker{display:none}
details.hoi summary::after{content:'+';position:absolute;right:4px;top:8px;font-size:22px;color:var(--do)}
details.hoi[open] summary::after{content:'–'}
details.hoi p{margin:0 0 14px;color:#3c3d42}
.ket-qua{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:16px}
.ket-qua figure{margin:0;border:1px solid var(--vien);border-radius:12px;overflow:hidden}
.ket-qua figcaption{padding:12px 14px;font-size:14.5px}.ket-qua figcaption b{display:block}
.ket-qua .kq-cap{display:flex}.ket-qua .kq-cap div{flex:1;aspect-ratio:7/8;background:center 20%/cover;position:relative}
.ket-qua .kq-cap span{position:absolute;left:8px;top:8px;background:var(--den);color:#fff;font-size:11px;font-weight:700;letter-spacing:.1em;padding:2px 7px;border-radius:4px}.ket-qua .kq-cap span.s{background:var(--do)}
.ket-qua figcaption b{font:800 22px var(--tieu)}
ul.do-luong li{margin:8px 0}
.app-ban{border-top:1px solid var(--vien);padding:40px 0 70px}
.app-goi{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:20px;margin:22px 0}
.app-goi>div{border:1px solid var(--vien);border-radius:14px;padding:22px}
.app-goi small{color:var(--do-dam);font-weight:700;letter-spacing:.1em;text-transform:uppercase;font-size:12px}.app-goi h3{margin:4px 0 8px;font-size:21px}
.gia-ny{font:800 34px var(--tieu)}.gia-ny span{font:500 14px var(--than);color:var(--chu2);margin-left:6px}
.app-goi ul{padding-left:18px;margin:10px 0 0;font-size:14.5px;color:#3c3d42}
.app-ud{background:var(--do-nhat);border-left:4px solid var(--do);border-radius:10px;padding:14px 18px;margin-bottom:20px;line-height:1.8}
.tom-mua{background:var(--nen2);border-radius:12px;padding:14px 16px;margin-bottom:18px;font-size:15px}
.gia-mua{font:800 32px var(--tieu);color:var(--do-dam);margin-top:4px}.gia-mua s{color:#9a9ba0;font-size:22px;margin-right:6px}
details.moi{border:1px solid var(--vien);border-radius:10px;padding:10px 14px;margin-bottom:16px}details.moi summary{cursor:pointer;font-weight:600;margin-bottom:6px}
.bon-o{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.hang-nut{display:flex;flex-wrap:wrap;gap:12px}
.hero-hoc{display:grid;grid-template-columns:1.1fr 1fr;gap:32px;align-items:center}
.hero-bia{width:100%;border-radius:16px;box-shadow:0 20px 40px #0007}
.chip-luoi{display:flex;flex-wrap:wrap;gap:10px;margin:4px 0 24px}.chip-luoi span{border:1px solid #ffffff3d;border-radius:999px;padding:8px 14px;font-weight:600;font-size:14.5px}
.hinh-chung{padding:34px 0 10px}
.hc-luoi{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.hc-luoi figure{margin:0;border:1px solid var(--vien);border-radius:14px;overflow:hidden;background:#fff}
.hc-luoi img{width:100%;aspect-ratio:4/3;object-fit:cover;object-position:top}
.hc-luoi figcaption{padding:12px 14px;font-size:14px;color:#3c3d42}.hc-luoi figcaption b{display:block;font-size:16.5px;color:var(--chu);margin-bottom:2px}
@media (max-width:900px){.hero-hoc{grid-template-columns:1fr}.hc-luoi{grid-template-columns:1fr 1fr}}
@media (max-width:600px){.hc-luoi{gap:10px}.hc-luoi figcaption{font-size:13px;padding:9px 10px}.hc-luoi figcaption b{font-size:15px}}