:root{
  --bg:#F3F7F6; --surface:#FFFFFF; --ink:#10212B; --muted:#56686F; --line:#DCE5E3;
  --teal:#0B6E6A; --teal-soft:#DDEFEC; --amber:#F2A93B; --brand:#0B6E6A;
  --f:"Be Vietnam Pro",system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#0C171D; --surface:#13232B; --ink:#EAF2F0; --muted:#9DB0B5; --line:#22353D;
  --teal:#3CC6BE; --teal-soft:#123A3B; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0C171D; --surface:#13232B; --ink:#EAF2F0; --muted:#9DB0B5; --line:#22353D;
  --teal:#3CC6BE; --teal-soft:#123A3B; color-scheme:dark}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:400 16px/1.7 var(--f);-webkit-font-smoothing:antialiased}
a{color:var(--teal)}
.wrap{max-width:760px;margin:0 auto;padding-inline:20px}
.wide{max-width:1120px}
:focus-visible{outline:2px solid var(--amber);outline-offset:3px;border-radius:6px}
[data-lang="en"] .vi,[data-lang="vi"] .en{display:none}

header{position:sticky;top:0;z-index:10;background:color-mix(in srgb,var(--bg) 90%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;gap:16px;height:64px}
.logo{height:30px;width:auto;display:block}
.logo.d{display:none}
@media (prefers-color-scheme:dark){.logo.l{display:none}.logo.d{display:block}}
.right{display:flex;align-items:center;gap:18px}
.right a{text-decoration:none;font-weight:500;font-size:15px;color:var(--muted)}
.right a:hover,.right a[aria-current]{color:var(--ink)}
.lang{display:flex;border:1px solid var(--line);border-radius:999px;overflow:hidden}
.lang button{all:unset;cursor:pointer;font:600 12px/1 var(--f);padding:8px 11px;color:var(--muted)}
.lang button[aria-pressed="true"]{background:var(--ink);color:var(--bg)}
@media (max-width:640px){.right a{display:none}}

main{padding-block:48px 64px}
h1{font-size:clamp(30px,5vw,42px);font-weight:800;letter-spacing:-.02em;line-height:1.15;margin:0 0 8px;text-wrap:balance}
.meta{color:var(--muted);font-size:14px;margin:0 0 32px}
h2{font-size:21px;font-weight:700;line-height:1.3;margin:40px 0 10px;scroll-margin-top:80px}
h3{font-size:17px;font-weight:600;margin:24px 0 6px}
p,li{color:var(--ink)}
ul,ol{padding-left:22px}
li{margin:4px 0}
.muted{color:var(--muted)}
.note{background:var(--teal-soft);border-radius:14px;padding:16px 18px;margin:20px 0}
.note p{margin:0}
.toc{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:16px 20px;margin:0 0 8px}
.toc ol{margin:0;padding-left:20px;columns:2;column-gap:28px}
@media (max-width:560px){.toc ol{columns:1}}
.toc li{margin:0 0 6px;break-inside:avoid}
.toc a{text-decoration:none;color:var(--ink)}
.toc a:hover{color:var(--teal)}
table{width:100%;border-collapse:collapse;font-size:15px;margin:12px 0}
th,td{text-align:left;vertical-align:top;padding:10px 12px;border-bottom:1px solid var(--line)}
th{font-weight:600;color:var(--muted);font-size:13px;text-transform:uppercase;letter-spacing:.05em}
.tbl{overflow-x:auto}
.cards{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin:20px 0}
@media (max-width:560px){.cards{grid-template-columns:1fr}}
.card{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:18px 20px;min-width:0}
.card .k{font-size:12px;font-weight:600;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.card .v{font-size:18px;font-weight:600;overflow-wrap:anywhere;margin-top:4px}
.card .v a{color:var(--ink);text-decoration:none}
.card p{margin:6px 0 0;color:var(--muted);font-size:14px}
details{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:4px 18px;margin:10px 0}
summary{cursor:pointer;font-weight:600;padding:12px 0}
details[open] summary{border-bottom:1px solid var(--line);margin-bottom:8px}
.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 20px;border-radius:12px;font-weight:600;text-decoration:none;background:var(--brand);color:#fff}
.btn:hover{background:var(--ink);color:var(--bg)}
.steps{counter-reset:s;list-style:none;padding:0}
.steps li{counter-increment:s;position:relative;padding-left:40px;margin:12px 0}
.steps li::before{content:counter(s);position:absolute;left:0;top:1px;width:26px;height:26px;border-radius:50%;background:var(--teal-soft);color:var(--teal);font-weight:700;font-size:14px;display:grid;place-items:center}
code{font-size:.92em;background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:1px 6px}

footer{padding-block:24px 40px;font-size:14px;color:var(--muted);border-top:1px solid var(--line)}
footer .wrap{display:flex;flex-wrap:wrap;gap:8px 20px;justify-content:space-between}
footer nav{display:flex;flex-wrap:wrap;gap:6px 16px}
footer a{color:var(--muted);text-decoration:none}
footer a:hover{color:var(--ink)}