:root { --blue:#3A7CC6; --dark:#1E3A5F; --light:#E8F4FD; --sky:#5BA3E6; --gray:#6B7280; --lgray:#F3F4F6; --orange:#F59E0B; --green:#22C55E; --text:#1f2a3a; --line:#d6e4f2; }
* { box-sizing: border-box; }
body { margin:0; background:#f4f8fc; color:var(--text); font:400 16px/1.65 'Inter', Arial, sans-serif; }
a { color:var(--blue); }
.wrap { max-width: 960px; margin: 0 auto; padding: 0 16px; }

nav.top { background:var(--dark); position:sticky; top:0; z-index:10; }
nav.top .wrap { display:flex; gap:4px; align-items:center; overflow-x:auto; padding-top:8px; padding-bottom:8px; }
nav.top a { color:#cfe0f2; text-decoration:none; font:600 14px 'Inter'; padding:6px 10px; border-radius:8px; white-space:nowrap; }
nav.top a:hover, nav.top a.on { background:rgba(255,255,255,.12); color:#fff; }
nav.top a.home { font-family:'Montserrat'; font-weight:800; color:#fff; margin-right:8px; }

header.hero { background: var(--blue); color:#fff; position:relative; overflow:hidden; }
header.hero::after { content:""; position:absolute; right:-120px; top:-60px; width:420px; height:420px; border-radius:50%; border:2px solid rgba(255,255,255,.16); }
header.hero::before { content:""; position:absolute; right:-20px; top:60px; width:220px; height:220px; border-radius:50%; background:rgba(255,255,255,.08); }
.hero .wrap { padding-top: 28px; padding-bottom: 40px; position:relative; z-index:1; }
.hero img.logo { height: 38px; }
.hero .nhan { display:inline-block; margin-top:28px; font:600 12px 'Inter'; letter-spacing:.14em; text-transform:uppercase; background:rgba(255,255,255,.16); padding:5px 12px; border-radius:999px; }
.hero h1 { font:800 clamp(28px,5vw,42px)/1.15 'Montserrat', Arial, sans-serif; margin:14px 0 10px; }
.hero p { margin:0; color:#e3f0fc; max-width:680px; font-size:17px; }
.chips { display:flex; flex-wrap:wrap; gap:10px; margin-top:24px; }
.chips span, .chips a { background:#fff; color:var(--dark); border-radius:10px; padding:8px 14px; font:600 14px 'Inter'; text-decoration:none; }
.chips b { color:var(--blue); font-family:'Montserrat'; }

main { padding: 28px 0 48px; }
.card { background:#fff; border:1px solid var(--line); border-radius:16px; padding:24px; margin-bottom:22px; box-shadow:0 4px 18px rgba(30,58,95,.06); }
.luoi { display:grid; grid-template-columns:repeat(3,1fr); gap:12px; margin:12px 0; }
.luoi > div, .luoi > a { background:var(--light); border-radius:12px; padding:14px; font-size:15px; color:var(--text); text-decoration:none; display:block; }
.luoi b { display:block; font:800 18px 'Montserrat'; color:var(--blue); margin-bottom:4px; }
.luoi i { display:block; font-style:normal; color:var(--gray); font-size:14px; margin-top:6px; }
@media (max-width:760px){ .luoi { grid-template-columns:1fr; } }

h2 { font:800 24px/1.3 'Montserrat', Arial, sans-serif; color:var(--dark); margin:0 0 6px; display:flex; gap:12px; align-items:center; }
h2 .so { flex:none; display:grid; place-items:center; width:40px; height:40px; border-radius:11px; background:var(--blue); color:#fff; font-size:18px; }
.dung { color:var(--gray); margin:0 0 14px; }
h3 { font:700 17px 'Montserrat', Arial, sans-serif; color:var(--blue); margin:20px 0 8px; }
ol, ul { padding-left:22px; margin:8px 0; }
li { margin:5px 0; }
.phut { display:inline-block; background:var(--dark); color:#fff; font:700 13px 'Montserrat'; border-radius:999px; padding:4px 12px; margin-bottom:8px; }
.link { display:inline-flex; gap:8px; align-items:center; background:var(--light); border-radius:8px; padding:6px 12px; font-weight:600; text-decoration:none; word-break:break-all; }
.nut { display:inline-block; background:var(--blue); color:#fff; text-decoration:none; font:700 15px 'Inter'; padding:10px 18px; border-radius:10px; margin:6px 8px 6px 0; }
.nut.phu { background:var(--light); color:var(--dark); }

.prompt { position:relative; background:#0f1e33; color:#e9f2ff; border-radius:12px; padding:16px; margin:10px 0; font:14.5px/1.6 'Inter', Arial, sans-serif; white-space:pre-wrap; }
.prompt .nhan-p { display:block; font:600 11.5px 'Inter'; letter-spacing:.1em; text-transform:uppercase; color:#8fc1f2; margin-bottom:6px; }
.prompt button { position:absolute; top:10px; right:10px; border:0; background:var(--blue); color:#fff; font:600 13px 'Inter'; padding:6px 12px; border-radius:8px; cursor:pointer; }
.prompt button.ok { background:var(--green); }
.prompt p { margin:0; padding-right:70px; }

.note { border-radius:10px; padding:12px 16px; margin:12px 0; font-size:15px; }
.note.vang { background:#fffbeb; border-left:4px solid var(--orange); }
.note.do { background:#fef2f2; border-left:4px solid #dc2626; }
.note.xanh { background:#f0fdf4; border-left:4px solid var(--green); }
.note.lam { background:var(--light); border-left:4px solid var(--blue); }
.note b { color:var(--dark); }

table { width:100%; border-collapse:collapse; font-size:15px; margin:10px 0; }
th { background:var(--dark); color:#fff; text-align:left; padding:9px 12px; font-weight:600; }
td { padding:9px 12px; border-bottom:1px solid var(--line); vertical-align:top; }
tr:nth-child(even) td { background:#f6faff; }
code { font:14px Consolas, monospace; background:#eef3f9; padding:1px 5px; border-radius:4px; word-break:break-word; }
.bang-cuon { overflow-x:auto; }
.cay { background:var(--lgray); border-radius:10px; padding:12px 16px; font:14px/1.7 Consolas, monospace; white-space:pre; overflow-x:auto; }
.check li { list-style:none; margin-left:-22px; padding-left:28px; position:relative; }
.check li::before { content:""; position:absolute; left:0; top:5px; width:16px; height:16px; border:2px solid var(--blue); border-radius:4px; }

footer { background:var(--dark); color:#cfe0f2; padding:24px 0; font-size:14px; }
footer .wrap { display:flex; justify-content:space-between; align-items:center; gap:16px; flex-wrap:wrap; }
footer img { height:28px; }
footer a { color:#fff; }