/* VARC shared styles */
html{-webkit-text-size-adjust:100%}
body{margin:0}
img{max-width:100%}
[hidden]{display:none!important}
/* Layout: banded sections on a 1200px column; one dark band (tech stack) as the anchor */
:root{
  --bg:#F7F6F2; --surface:#FFFFFF; --tint:#EEF3F2; --fg:#0F1B2D; --muted:#3D4756; --soft:#5A6473;
  --line:#DAD7CE; --line-soft:#E7E4DB; --accent:#0E6E63; --accent-hover:#0A4F47; --on-accent:#FFFFFF;
  --band:#0F1B2D; --band-2:#16253A; --band-line:#2B3A50; --band-fg:#F7F6F2; --band-muted:#C9D1DC; --band-accent:#9FD8CF;
  --warn:#8A5A00; --band-warn:#F2C46D; --input:#9AA3AE;
  --display:'Source Serif 4',Georgia,'Times New Roman',serif;
  --body:'Be Vietnam Pro',system-ui,-apple-system,'Segoe UI',sans-serif;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#0E1622; --surface:#152132; --tint:#13262A; --fg:#E9EDF2; --muted:#B8C2CE; --soft:#98A4B3;
  --line:#2A3A4F; --line-soft:#223246; --accent:#4FB8A8; --accent-hover:#79CFC2; --on-accent:#08201D;
  --band:#08101A; --band-2:#0F1B2A; --band-line:#22334A; --band-fg:#E9EDF2; --band-muted:#B8C2CE; --band-accent:#9FD8CF;
  --warn:#E8B860; --band-warn:#F2C46D; --input:#5A6A7E; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0E1622; --surface:#152132; --tint:#13262A; --fg:#E9EDF2; --muted:#B8C2CE; --soft:#98A4B3;
  --line:#2A3A4F; --line-soft:#223246; --accent:#4FB8A8; --accent-hover:#79CFC2; --on-accent:#08201D;
  --band:#08101A; --band-2:#0F1B2A; --band-line:#22334A; --band-fg:#E9EDF2; --band-muted:#B8C2CE; --band-accent:#9FD8CF;
  --warn:#E8B860; --band-warn:#F2C46D; --input:#5A6A7E; color-scheme:dark}

*{box-sizing:border-box}
body{background:var(--bg);color:var(--fg);font-family:var(--body);font-size:16px;line-height:1.6}
a{color:var(--accent)}a:hover{color:var(--accent-hover)}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:4px}
h1,h2,h3,p{margin:0}
h1,h2{font-family:var(--display);font-weight:600;text-wrap:balance}
h1{font-size:clamp(2.1rem,4.6vw,3.25rem);line-height:1.15;letter-spacing:-.01em}
h2{font-size:clamp(1.6rem,3vw,2.125rem);line-height:1.25}
h3{font-size:1.25rem;line-height:1.35;text-wrap:balance}
.wrap{max-width:1200px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}
.section{padding-block:88px}
.band{background:var(--surface);border-block:1px solid var(--line)}
.eyebrow{font-size:.8125rem;font-weight:600;letter-spacing:.12em;text-transform:uppercase;color:var(--accent)}
.lede{color:var(--muted);max-width:44rem}
.stack{display:flex;flex-direction:column}
.head{display:flex;flex-direction:column;gap:12px;margin-bottom:40px}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:46px;padding:0 22px;border-radius:8px;font:600 15px/1 var(--body);text-decoration:none;border:1px solid transparent;cursor:pointer}
.btn-primary{background:var(--accent);color:var(--on-accent)}
.btn-primary:hover{background:var(--accent-hover);color:var(--on-accent)}
.btn-ghost{border-color:var(--fg);color:var(--fg);background:transparent}
.btn-ghost:hover{background:var(--fg);color:var(--bg)}
.grid{display:grid;gap:20px;grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}
.card{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:24px;display:flex;flex-direction:column;gap:8px}
.card p{color:var(--muted);font-size:.9375rem}
.card .q{font-weight:600;color:var(--fg);font-size:1rem}
.meta{font-size:.875rem;color:var(--soft)}

/* header */
header{background:var(--bg);border-bottom:1px solid var(--line);position:sticky;top:env(safe-area-inset-top,0px);z-index:5}
body::before{content:"";position:fixed;inset:0 0 auto;height:env(safe-area-inset-top,0px);z-index:10;background:var(--bg)}
.bar{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px 20px;padding-block:14px}
.logo{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--fg)}
.mark{display:inline-flex;width:36px;height:36px;border-radius:8px;background:var(--fg);color:var(--bg);align-items:center;justify-content:center;font-weight:700}
.logo b{display:block;font-size:18px;letter-spacing:.04em;line-height:1.2}
.logo small{display:block;font-size:12px;color:var(--soft);line-height:1.2}
nav.main{display:flex;flex-wrap:wrap;gap:4px 22px;font-size:15px}
nav.main a{color:var(--fg);text-decoration:none}
nav.main a:hover{color:var(--accent)}
.tools{display:flex;align-items:center;gap:10px}
.lang{display:inline-flex;border:1px solid var(--line);border-radius:8px;overflow:hidden}
.lang button{min-height:44px;min-width:44px;padding:0 12px;border:0;background:transparent;color:var(--soft);font:600 14px var(--body);cursor:pointer}
.lang button[aria-pressed="true"]{background:var(--fg);color:var(--bg)}
@media (max-width:860px){nav.main{order:3;width:100%}}

/* hero */
.hero{padding-block:80px 64px;display:flex;flex-wrap:wrap;gap:48px;align-items:flex-start}
.hero-main{flex:999 1 560px;min-width:0;display:flex;flex-direction:column;gap:24px}
.hero-main .lede{font-size:1.1875rem}
.paths{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:16px;max-width:680px;margin-top:12px}
.path{display:flex;flex-direction:column;gap:6px;padding:22px;border-radius:12px;text-decoration:none;border:1px solid var(--fg);color:var(--fg);background:var(--surface)}
.path.dark{background:var(--band);border-color:var(--band);color:var(--band-fg)}
.path span:first-child{font-size:.8125rem;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--accent)}
.path.dark span:first-child{color:var(--band-accent)}
.path strong{font-size:1.25rem}
.path span:last-child{font-size:.875rem;color:var(--muted)}
.path.dark span:last-child{color:var(--band-muted)}
.path:hover{transform:translateY(-2px)}
.watch{flex:1 1 320px;min-width:0;background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:28px;display:flex;flex-direction:column;gap:18px}
.watch ul{list-style:none;margin:0;padding:0;display:flex;flex-direction:column}
.watch li{padding-block:16px;border-bottom:1px solid var(--line-soft);display:flex;flex-direction:column;gap:4px}
.watch li:first-child{padding-top:0}
.watch li:last-child{border-bottom:0;padding-bottom:0}
.watch li strong{font-size:1rem}
.watch li span{font-size:.875rem;color:var(--muted)}
.watch .note{font-size:.8125rem;color:var(--soft)}

/* two-way */
.twoway{display:flex;flex-wrap:wrap;gap:32px}
.twoway > div{flex:1 1 440px;min-width:0;display:flex;flex-direction:column;gap:12px}
.twoway h3{font-size:1.5rem;margin-bottom:8px}

/* knowledge */
a.card{text-decoration:none;color:var(--fg)}
a.card:hover{border-color:var(--accent)}
a.card .t{font-size:1.25rem;font-weight:600;line-height:1.35}
.kind{font-size:.75rem;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--accent)}

/* tech stack band */
.dark-band{background:var(--band);color:var(--band-fg)}
.dark-band .eyebrow{color:var(--band-accent)}
.dark-band .lede{color:var(--band-muted)}
.dark-band a{color:var(--band-accent)}
.split{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:flex-end;gap:16px;margin-bottom:36px}
.split > div{max-width:44rem;display:flex;flex-direction:column;gap:12px}
.table-box{overflow-x:auto;border:1px solid var(--band-line);border-radius:12px}
table{width:100%;min-width:720px;border-collapse:collapse;font-size:.9375rem}
th{background:var(--band-2);text-align:left;font-weight:600;padding:16px 20px}
td{padding:16px 20px;border-top:1px solid var(--band-line);color:var(--band-muted);vertical-align:top}
td:first-child{color:var(--band-fg);font-weight:600}
td.status{color:var(--band-warn);white-space:nowrap}

/* regulation */
.reg{display:flex;flex-wrap:wrap;gap:24px}
.feature{flex:999 1 520px;min-width:0;background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:36px;display:flex;flex-direction:column;gap:16px}
.feature h3{font-family:var(--display);font-size:clamp(1.4rem,2.4vw,1.75rem);line-height:1.3}
.feature p{color:var(--muted)}
.feature .meta{display:flex;flex-wrap:wrap;gap:6px 24px}
.feature .btn{align-self:flex-start}
.reg-list{flex:1 1 320px;min-width:0;display:flex;flex-direction:column;gap:16px}
.reg-list .card h3{font-size:1.0625rem;line-height:1.4}

/* formats */
.price{font-weight:600;color:var(--fg)!important}
.soon{margin-top:32px;padding:28px;border-radius:12px;background:var(--tint);display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:20px}
.soon > div{flex:999 1 420px;min-width:0;display:flex;flex-direction:column;gap:6px}
.soon .label{font-size:.8125rem;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--warn)}
.soon p:last-child{font-size:1.0625rem}

/* commitments */
.commit{border-top:2px solid var(--accent);padding-top:18px;display:flex;flex-direction:column;gap:8px}
.commit p{color:var(--muted);font-size:.9375rem}

/* forms */
.newsletter{background:var(--tint);border-block:1px solid var(--line)}
.nl{display:flex;flex-wrap:wrap;gap:40px;align-items:center;padding-block:64px}
.nl > div{flex:999 1 460px;min-width:0;display:flex;flex-direction:column;gap:12px}
.nl h2{font-size:clamp(1.4rem,2.4vw,1.75rem);line-height:1.3}
.nl form{flex:1 1 360px;min-width:0}
form{display:flex;flex-direction:column;gap:14px}
label.l{font-weight:600;font-size:.875rem}
.field{display:flex;flex-direction:column;gap:6px}
input[type=text],input[type=email],select,textarea{min-height:46px;padding:0 12px;border:1px solid var(--input);border-radius:8px;font:16px var(--body);background:var(--surface);color:var(--fg);width:100%}
textarea{padding:12px;resize:vertical;min-height:120px}
.inline{display:flex;flex-wrap:wrap;gap:10px}
.inline input{flex:1 1 220px;width:auto}
.consent{display:flex;gap:10px;align-items:flex-start;font-size:.875rem;color:var(--muted)}
.consent input{width:20px;height:20px;margin:2px 0 0;flex:0 0 auto;accent-color:var(--accent)}
fieldset{margin:0;padding:0;border:0;display:flex;flex-direction:column;gap:6px}
legend{font-weight:600;font-size:.875rem;margin-bottom:6px}
.radios{display:flex;flex-wrap:wrap;gap:4px 24px}
.radios label{display:flex;align-items:center;gap:8px;min-height:44px}
.radios input{width:18px;height:18px;accent-color:var(--accent)}
.form-msg{font-size:.875rem;color:var(--accent);min-height:1.4em}
.form-msg.err{color:#B42318}
:root[data-theme="dark"] .form-msg.err{color:#FF8A80}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .form-msg.err{color:#FF8A80}}
.contact{display:flex;flex-wrap:wrap;gap:48px;align-items:flex-start}
.contact > div{flex:1 1 320px;min-width:0;display:flex;flex-direction:column;gap:16px}
.contact > form{flex:999 1 560px;min-width:0;background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:32px;gap:18px}
.contact dl{margin:8px 0 0;display:flex;flex-direction:column;gap:8px;font-size:.9375rem;color:var(--muted)}
.contact dt{font-weight:600;color:var(--fg)}
.contact dd{margin:0 0 6px}
.two{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px}
@media (max-width:480px){.contact > form{padding:20px}.feature{padding:24px}}

/* footer */
footer{background:var(--band);color:var(--band-muted)}
.foot{padding-block:48px 40px;display:flex;flex-direction:column;gap:24px}
.foot-top{display:flex;flex-wrap:wrap;justify-content:space-between;gap:24px}
.foot-top > div{max-width:28rem;display:flex;flex-direction:column;gap:8px;font-size:.875rem}
.foot-top b{color:var(--band-fg);font-size:18px;letter-spacing:.04em}
footer nav{display:flex;flex-wrap:wrap;gap:8px 24px;font-size:.875rem}
footer nav a{color:var(--band-fg)}
.legal{padding-top:24px;border-top:1px solid var(--band-line);font-size:.8125rem}
@media (prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}
@media (prefers-reduced-motion:no-preference){html{scroll-behavior:smooth}.path{transition:transform .15s}}

/* ---------- multi-page additions ---------- */
html[lang="vi"] [data-l="en"],html[lang="en"] [data-l="vi"]{display:none!important}
nav.main a[aria-current="page"]{color:var(--accent);font-weight:600}
.skip{position:absolute;left:-9999px;top:0;background:var(--fg);color:var(--bg);padding:10px 14px;z-index:20}
.skip:focus{left:max(16px,env(safe-area-inset-left,0px));top:calc(env(safe-area-inset-top,0px) + 8px)}

.page-hero{border-bottom:1px solid var(--line);background:var(--surface)}
.page-hero .wrap{padding-block:56px 48px;display:flex;flex-direction:column;gap:16px}
.page-hero h1{font-size:clamp(1.9rem,4vw,2.75rem);max-width:22ch}
.page-hero .lede{font-size:1.125rem}
.crumbs{display:flex;flex-wrap:wrap;gap:6px;font-size:.875rem;color:var(--soft)}
.crumbs a{color:var(--soft)}
.crumbs span[aria-hidden]{opacity:.6}
.page-hero.dark{background:var(--band);color:var(--band-fg);border-bottom:0}
.page-hero.dark .lede,.page-hero.dark .crumbs,.page-hero.dark .crumbs a{color:var(--band-muted)}
.page-hero.dark .eyebrow{color:var(--band-accent)}

.layout{display:flex;flex-wrap:wrap;gap:48px;align-items:flex-start;padding-block:56px 88px}
.toc{flex:1 1 220px;min-width:0;position:sticky;top:calc(env(safe-area-inset-top,0px) + 96px);display:flex;flex-direction:column;gap:10px;font-size:.9375rem}
.toc p{font-size:.75rem;font-weight:600;letter-spacing:.1em;text-transform:uppercase;color:var(--soft)}
.toc a{color:var(--muted);text-decoration:none}
.toc a:hover{color:var(--accent)}
.toc ol{margin:0;padding-left:18px;display:flex;flex-direction:column;gap:8px}
@media (max-width:860px){.toc{position:static}}
.content{flex:999 1 620px;min-width:0;display:flex;flex-direction:column;gap:56px}

.prose{max-width:46rem;display:flex;flex-direction:column;gap:16px}
.prose h2{margin-top:8px;scroll-margin-top:110px}
.prose h3{margin-top:8px;font-size:1.1875rem}
.prose p,.prose li{color:var(--muted)}
.prose strong{color:var(--fg)}
.prose ul,.prose ol{margin:0;padding-left:22px;display:flex;flex-direction:column;gap:8px}
.prose .table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:10px}
.prose table{min-width:560px;color:var(--fg)}
.prose th{background:var(--tint);color:var(--fg)}
.prose td{border-top:1px solid var(--line);color:var(--muted)}
.prose td:first-child{color:var(--fg)}
.anchor-sec{scroll-margin-top:110px;display:flex;flex-direction:column;gap:20px}

.callout{border:1px solid var(--line);background:var(--tint);border-radius:12px;padding:20px 22px;display:flex;flex-direction:column;gap:8px}
.callout strong{color:var(--fg)}
.callout p{color:var(--muted)}
.callout.warn{background:var(--surface);border-color:var(--warn)}
.callout.warn .label{color:var(--warn);font-size:.75rem;font-weight:600;letter-spacing:.1em;text-transform:uppercase}

.checklist{list-style:none!important;padding:0!important}
.checklist li{display:flex;gap:12px;align-items:flex-start}
.checklist li::before{content:"";flex:0 0 18px;height:18px;margin-top:3px;border:1.5px solid var(--accent);border-radius:4px}

.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{min-height:40px;padding:0 16px;border:1px solid var(--line);border-radius:999px;background:var(--surface);color:var(--fg);font:500 14px var(--body);cursor:pointer}
.chip[aria-pressed="true"]{background:var(--fg);color:var(--bg);border-color:var(--fg)}
.tag{display:inline-flex;align-items:center;height:24px;padding:0 10px;border-radius:999px;background:var(--tint);color:var(--accent);font-size:.75rem;font-weight:600}
.reg-row{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:8px 24px;padding-block:20px;border-top:1px solid var(--line)}
.reg-row:last-child{border-bottom:1px solid var(--line)}
.reg-row h3{font-size:1.0625rem}
.reg-row p{color:var(--muted);font-size:.9375rem}
.reg-row .side{display:flex;flex-direction:column;align-items:flex-end;gap:6px;text-align:right}
.reg-row .tags{display:flex;flex-wrap:wrap;gap:6px}
@media (max-width:640px){.reg-row{grid-template-columns:1fr}.reg-row .side{align-items:flex-start;text-align:left}}
.empty{color:var(--soft);padding-block:24px}

.search{max-width:28rem}
.gloss{margin:0;display:flex;flex-direction:column}
.gloss > div{display:grid;grid-template-columns:minmax(0,14rem) minmax(0,1fr);gap:6px 32px;padding-block:18px;border-top:1px solid var(--line)}
.gloss dt{font-weight:600}
.gloss dt span{display:block;font-weight:500;color:var(--accent);font-size:.9375rem}
.gloss dd{margin:0;color:var(--muted)}
@media (max-width:640px){.gloss > div{grid-template-columns:1fr}}

.layer{display:flex;flex-direction:column;gap:16px;padding-block:40px;border-top:1px solid var(--line);scroll-margin-top:110px}
.layer:first-child{border-top:0;padding-top:0}
.layer-head{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:baseline;gap:8px 16px}
.facts{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px}
.facts > div{display:flex;flex-direction:column;gap:6px}
.facts dt,.facts .k{font-size:.75rem;font-weight:600;letter-spacing:.08em;text-transform:uppercase;color:var(--soft)}
.facts p,.facts ul{color:var(--muted);font-size:.9375rem;margin:0}
.facts ul{padding-left:18px}

.steps{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:24px;counter-reset:s}
.steps li{border-top:2px solid var(--accent);padding-top:16px;display:flex;flex-direction:column;gap:6px;counter-increment:s}
.steps li::before{content:counter(s,decimal-leading-zero);font-size:.8125rem;font-weight:600;color:var(--accent)}
.steps p{color:var(--muted);font-size:.9375rem}

details.faq{border-top:1px solid var(--line);padding-block:4px}
details.faq:last-of-type{border-bottom:1px solid var(--line)}
details.faq summary{cursor:pointer;min-height:52px;display:flex;align-items:center;font-weight:600;list-style:none;gap:12px}
details.faq summary::-webkit-details-marker{display:none}
details.faq summary::after{content:"+";margin-left:auto;font-size:1.25rem;color:var(--accent)}
details.faq[open] summary::after{content:"–"}
details.faq p{color:var(--muted);padding-bottom:16px;max-width:46rem}

.hp{position:absolute!important;left:-9999px!important;width:1px;height:1px;overflow:hidden}
.btn[disabled]{opacity:.6;cursor:progress}
.center-page{min-height:60vh;display:flex;flex-direction:column;justify-content:center;gap:16px;padding-block:80px}
.foot-cols{display:flex;flex-wrap:wrap;gap:16px 48px}
.foot-cols div{display:flex;flex-direction:column;gap:8px;font-size:.875rem}
.foot-cols p{color:var(--band-fg);font-weight:600}
.foot-cols a{color:var(--band-muted);text-decoration:none}
.foot-cols a:hover{color:var(--band-fg)}