/* DataLine Viet Nam introduction site.
   Colours, type and layout follow EduFite's website (white and navy), owner's decision 2026-11-13.
   Palette: brand/BRAND_GUIDE.md section 8. Navy #14325A on white measures 12.85:1. */

:root {
  --white: #FFFFFF;
  --tint: #EEF3F9;      /* navy wash: panels and cards */
  --tint2: #F6F8FB;     /* alternate section background */
  --navy: #14325A;      /* brand navy */
  --navy2: #0F2949;     /* hover on navy */
  --deep: #0A1F38;      /* darkest navy: dark bands, footer */
  --mid: #2F5A8A;       /* navy mid: eyebrows, accents, never text on dark */
  --text: #334155;
  --head: #14325A;
  --muted: #5B6B80;
  --line: #D8E0EA;      /* decorative lines only */
  --on-dark: #D3DDE9;
  --on-dark-soft: #9FB3CC;
  --radius: 16px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }
body {
  font-family: Manrope, system-ui, -apple-system, "Segoe UI", sans-serif;
  font-weight: 500;
  background: var(--white);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
:focus-visible { outline: 3px solid var(--mid); outline-offset: 3px; border-radius: 6px; }

.wrap { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.skip { position: absolute; left: -9999px; top: 8px; background: var(--navy); color: #fff; padding: 8px 14px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 8px; }

.eyebrow { font-size: 13px; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; color: var(--mid); }
h1, h2, h3 { color: var(--head); }
h1 { font-size: clamp(34px, 5vw, 56px); font-weight: 800; line-height: 1.1; letter-spacing: -.025em; }
h2 { font-size: clamp(28px, 3.4vw, 40px); font-weight: 800; line-height: 1.18; letter-spacing: -.02em; }
h3 { font-size: 20px; font-weight: 800; line-height: 1.3; }
.lead { font-size: 18px; color: var(--muted); max-width: 36rem; }

.btn { display: inline-flex; align-items: center; gap: 8px; border-radius: 10px; font-weight: 700; font-size: 16px; padding: 14px 24px; transition: transform .15s, background .15s; }
.btn svg { width: 18px; height: 18px; stroke: currentColor; fill: none; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.btn-primary { background: var(--navy); color: #fff; }
.btn-primary:hover { background: var(--navy2); transform: translateY(-1px); }
.btn-ghost { border: 1.5px solid var(--navy); color: var(--navy); background: #fff; }
.btn-ghost:hover { background: var(--tint); }

section { padding: 96px 0; border-top: 1px solid var(--line); }
.alt { background: var(--tint2); }

/* Navigation */
.nav { position: sticky; top: 0; z-index: 40; background: rgba(255, 255, 255, .95); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.nav .wrap { display: flex; align-items: center; gap: 28px; height: 72px; }
.nav .logo img { height: 40px; width: auto; }
.nav .links { display: flex; gap: 26px; font-size: 15px; font-weight: 700; color: var(--navy); margin-left: auto; }
.nav .links a:hover { color: var(--mid); }
.nav .btn { padding: 10px 18px; font-size: 15px; }

/* Hero */
.hero { padding: 88px 0 96px; border-top: 0; background: linear-gradient(180deg, #fff 0%, var(--tint2) 100%); }
.hero .grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 56px; align-items: center; }
.hero h1 { margin: 16px 0 22px; }
.cta { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 32px; }

.panel { background: #fff; border: 1px solid var(--line); border-radius: 18px; padding: 28px; box-shadow: 0 24px 60px rgba(20, 50, 90, .12); }
.panel h2 { font-size: 18px; letter-spacing: 0; margin-bottom: 6px; }
.panel > p { font-size: 14px; color: var(--muted); margin-bottom: 18px; }
.tasks { list-style: none; display: grid; gap: 12px; }
.tasks li { display: flex; align-items: center; gap: 14px; padding: 14px 16px; background: var(--tint2); border: 1px solid var(--line); border-radius: 12px; font-size: 15px; font-weight: 600; color: var(--navy); }

.icon { flex: none; width: 42px; height: 42px; border-radius: 10px; background: var(--tint); display: grid; place-items: center; }
.icon svg { width: 22px; height: 22px; stroke: var(--navy); fill: none; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.tasks .icon { width: 36px; height: 36px; background: #fff; }
.tasks .icon svg { width: 19px; height: 19px; }

/* Section heads */
.head { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: end; margin-bottom: 44px; }
.head h2 { margin-top: 12px; }
.head p { color: var(--muted); }

/* Cards */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; transition: border-color .2s, transform .2s, box-shadow .2s; }
.card:hover { border-color: var(--navy); transform: translateY(-3px); box-shadow: 0 14px 36px rgba(20, 50, 90, .10); }
.card .icon { margin-bottom: 18px; }
.card p { color: var(--muted); font-size: 15px; margin: 10px 0 16px; }
.card ul { list-style: none; display: grid; gap: 8px; font-size: 15px; }
.card li { display: flex; gap: 10px; }
.card li::before { content: ""; flex: none; width: 6px; height: 6px; border-radius: 50%; background: var(--navy); margin-top: 10px; }

/* Audience */
.people { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.person { display: flex; gap: 16px; align-items: flex-start; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 24px; }
.person h3 { font-size: 17px; }
.person p { color: var(--muted); font-size: 15px; margin-top: 6px; }

/* Steps */
.steps { list-style: none; display: grid; grid-template-columns: repeat(3, 1fr); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: #fff; }
.step { padding: 30px; border-right: 1px solid var(--line); }
.step:last-child { border-right: 0; }
.step .n { font-size: 56px; font-weight: 800; color: #C9D5E3; line-height: 1; margin-bottom: 18px; }
.step p { color: var(--muted); font-size: 15px; margin-top: 10px; }

/* Learning rhythm */
.rhythm { display: grid; grid-template-columns: .8fr 1.2fr; gap: 40px; align-items: start; margin-top: 28px; padding: 30px; background: var(--tint); border-radius: var(--radius); }
.rhythm > div p { color: var(--muted); font-size: 15px; margin-top: 8px; }
.rhythm ol { list-style: none; counter-reset: r; display: grid; gap: 12px; }
.rhythm li { counter-increment: r; display: flex; gap: 14px; align-items: baseline; font-size: 15px; }
.rhythm li::before { content: counter(r); flex: none; width: 28px; height: 28px; border-radius: 50%; background: var(--navy); color: #fff; font-weight: 800; font-size: 14px; display: grid; place-items: center; transform: translateY(6px); }
.rhythm b { color: var(--navy); font-weight: 800; }

/* Scope */
.scope { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.scope-col { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; }
.scope-col h3 { margin-bottom: 14px; }
.scope ul { list-style: none; display: grid; gap: 10px; font-size: 15px; }
.scope li { display: flex; gap: 12px; }
.scope li::before { flex: none; width: 22px; height: 22px; border-radius: 50%; display: grid; place-items: center; font-size: 13px; font-weight: 800; margin-top: 1px; }
.scope .yes li::before { content: "\2713"; background: var(--navy); color: #fff; }
.scope .no li::before { content: "\00D7"; background: var(--tint); color: var(--navy); border: 1px solid var(--line); }

/* Founder */
.founder { display: grid; grid-template-columns: 220px 1fr; gap: 40px; align-items: center; max-width: 920px; }
.founder-photo { width: 220px; aspect-ratio: 1; border-radius: 18px; background: var(--tint); border: 1px solid var(--line); display: grid; place-items: center; color: var(--muted); font-weight: 700; overflow: hidden; }
.founder-photo img { width: 100%; height: 100%; object-fit: cover; }
.founder h2 { margin-top: 10px; }
.founder-role { color: var(--mid); font-weight: 700; margin: 4px 0 14px; }
.creds { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }
.founder { align-items: start; max-width: 1040px; }
.founder-lead { font-size: 17px; }
.highlights { list-style: none; display: grid; gap: 12px; margin-top: 20px; }
.highlights li { border-left: 3px solid var(--navy); padding: 2px 0 2px 16px; }
.highlights h3 { font-size: 16px; }
.highlights p { color: var(--muted); font-size: 15px; margin-top: 4px; }
.cred-groups { display: grid; gap: 14px; margin-top: 24px; }
.cred-groups h3 { font-size: 13px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--mid); }
.cred-groups .creds { margin-top: 8px; }
.founder.no-photo { grid-template-columns: 1fr; max-width: 820px; }
.founder-link { margin-top: 16px; font-weight: 700; }
.founder-link a { color: var(--navy); text-decoration: underline; text-underline-offset: 3px; }
.creds li { background: var(--tint); color: var(--navy); font-size: 14px; font-weight: 700; padding: 6px 12px; border-radius: 99px; }

/* FAQ */
.faq { display: grid; grid-template-columns: .8fr 1.2fr; gap: 48px; }
.faq h2 { margin-top: 12px; }
details { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 18px 22px; margin-bottom: 10px; }
summary { cursor: pointer; font-weight: 700; color: var(--navy); list-style: none; display: flex; justify-content: space-between; gap: 16px; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; color: var(--mid); font-weight: 800; }
details[open] summary::after { content: "\2212"; }
details p { color: var(--muted); margin-top: 12px; font-size: 15px; }

/* Principles band */
.band-lead { margin-top: 16px; font-size: 17px; }
.band { background: var(--deep); border-top: 0; color: var(--on-dark); }
.band .eyebrow { color: var(--on-dark-soft); }
.band h2 { color: #fff; margin-top: 12px; }
.band .grid { display: grid; grid-template-columns: .9fr 1.1fr; gap: 56px; align-items: start; }
.principles { list-style: none; display: grid; gap: 14px; }
.principles li { border: 1px solid rgba(255, 255, 255, .16); border-radius: 14px; padding: 20px 22px; }
.principles h3 { color: #fff; font-size: 18px; }
.principles p { margin-top: 6px; font-size: 15px; }

/* Contact */
.final { text-align: center; background: var(--tint); }
.final h2 { font-size: clamp(30px, 4.4vw, 48px); }
.final p { color: var(--muted); margin: 16px auto 30px; max-width: 36rem; }
.final .cta { justify-content: center; }

/* Footer */
.footer { background: var(--deep); padding: 56px 0 40px; font-size: 14px; color: #B7C4D4; }
.footer .cols { display: grid; grid-template-columns: 1.6fr 1fr 1fr; gap: 32px; }
.footer img { height: 40px; width: auto; margin-bottom: 16px; }
.footer h2 { font-size: 13px; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; color: var(--on-dark-soft); margin-bottom: 14px; }
.footer ul { list-style: none; display: grid; gap: 8px; }
.footer a:hover { color: #fff; }
.footer .legal { margin-top: 40px; padding-top: 22px; border-top: 1px solid rgba(255, 255, 255, .14); font-size: 13px; color: var(--on-dark-soft); display: grid; gap: 4px; }

/* Document pages (privacy policy) */
.nav-back { margin-left: auto; padding: 9px 16px; font-size: 14px; }
.doc { padding: 64px 0 96px; }
.doc-wrap { max-width: 760px; }
.doc h1 { margin: 12px 0 8px; font-size: clamp(32px, 4.4vw, 44px); }
.doc-meta { color: var(--muted); font-size: 14px; margin-bottom: 32px; }
.doc h2 { font-size: 22px; margin: 36px 0 12px; letter-spacing: 0; }
.doc h3 { font-size: 17px; margin: 18px 0 6px; }
.doc p, .doc li { font-size: 16px; }
.doc p + p { margin-top: 10px; }
.doc ul { margin: 10px 0 10px 22px; display: grid; gap: 6px; }
.doc a { color: var(--navy); text-decoration: underline; text-underline-offset: 2px; }
.doc .footer .legal, .footer .legal:first-child { margin-top: 0; padding-top: 0; border-top: 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn, .card { transition: none; }
  .btn:hover, .card:hover { transform: none; }
}

@media (max-width: 900px) {
  .hero .grid, .head, .band .grid, .rhythm, .scope, .faq { grid-template-columns: 1fr; }
  .rhythm, .faq { gap: 20px; }
  .founder { grid-template-columns: 1fr; gap: 24px; }
  .founder-photo { width: 160px; }
  .head { gap: 16px; }
  .cards, .people, .steps { grid-template-columns: 1fr; }
  .step { border-right: 0; border-bottom: 1px solid var(--line); }
  .step:last-child { border-bottom: 0; }
  .footer .cols { grid-template-columns: 1fr 1fr; }
  .footer .about { grid-column: 1 / -1; }
  .nav .links { display: none; }
  .nav .btn { margin-left: auto; }
}

@media (max-width: 520px) {
  section { padding: 72px 0; }
  .hero { padding: 56px 0 72px; }
  .wrap { padding: 0 16px; }
  .nav .wrap { gap: 12px; }
  .nav .btn { padding: 9px 14px; font-size: 14px; }
  .panel { padding: 20px; }
  .btn { width: 100%; justify-content: center; }
  .nav .btn { width: auto; }
}