/* ===== Học Tiếng Tiều · KangXi — design system v2 (teal, khớp app) ===== */
:root {
  color-scheme: light dark;
  --teal: #14B8A6;
  --teal-deep: #0E8A7D;
  --coral: #FF6B6B;
  --amber: #F59E0B;
  --bg: #F6F8FA;
  --card: #ffffff;
  --ink: #1B2632;
  --text: #1B2632;
  --muted: #5B6B7C;
  --line: #E3E9EF;
  --shadow: 0 18px 50px rgba(27, 38, 50, .10);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #10161B;
    --card: #1A2229;
    --ink: #F2F6F9;
    --text: #F2F6F9;
    --muted: #9FB0BF;
    --line: #2A343D;
    --shadow: 0 18px 50px rgba(0, 0, 0, .45);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16.5px/1.65 "Be Vietnam Pro", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--teal-deep); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; display: block; }

/* ---------- khung trang tài liệu (privacy/terms/support) ---------- */
main { width: min(860px, calc(100% - 32px)); margin: 40px auto 72px; }
header, article {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 22px;
  padding: 34px clamp(20px, 5vw, 44px);
  box-shadow: var(--shadow);
}
.eyebrow {
  display: inline-block;
  font-size: 12px; font-weight: 800; letter-spacing: .14em; text-transform: uppercase;
  color: var(--teal-deep);
  background: color-mix(in srgb, var(--teal) 12%, transparent);
  padding: 5px 12px; border-radius: 999px; margin-bottom: 14px;
}
article h1, header h1 { font-size: clamp(26px, 4.5vw, 34px); line-height: 1.2; margin: 0 0 14px; letter-spacing: -.01em; }
article h2 { font-size: 19px; margin: 28px 0 8px; }
article ul { padding-left: 20px; }
article li { margin: 6px 0; }
.lang { border-top: 1px dashed var(--line); margin-top: 34px; padding-top: 10px; }
.lang h1 { font-size: 24px; margin-top: 18px; }
article nav, header nav { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
article nav a, header nav a {
  border: 1px solid var(--line); border-radius: 999px; padding: 9px 16px;
  font-weight: 600; font-size: 14px; color: var(--text);
}
article nav a:hover, header nav a:hover { border-color: var(--teal); color: var(--teal-deep); text-decoration: none; }

/* ================= LANDING ================= */
.landing { width: 100%; margin: 0; }
.wrap { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }

/* topbar */
.topbar { position: sticky; top: 0; z-index: 50; backdrop-filter: blur(14px);
  background: color-mix(in srgb, var(--bg) 82%, transparent); border-bottom: 1px solid var(--line); }
.topbar .wrap { display: flex; align-items: center; gap: 14px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 17px; color: var(--text); }
.brand img { width: 34px; height: 34px; border-radius: 9px; }
.topnav { margin-left: auto; display: flex; gap: 22px; align-items: center; }
.topnav a { color: var(--muted); font-weight: 600; font-size: 14.5px; }
.topnav a:hover { color: var(--teal-deep); text-decoration: none; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--teal); color: #fff !important; font-weight: 700; font-size: 15px;
  padding: 11px 20px; border-radius: 999px; box-shadow: 0 8px 22px rgba(20, 184, 166, .35);
  transition: transform .15s ease, box-shadow .15s ease;
}
.btn:hover { transform: translateY(-1px); box-shadow: 0 12px 26px rgba(20, 184, 166, .45); text-decoration: none; }
.btn.ghost { background: transparent; color: var(--text) !important; border: 1.5px solid var(--line); box-shadow: none; }
.btn.ghost:hover { border-color: var(--teal); color: var(--teal-deep) !important; }

/* hero */
.hero { position: relative; overflow: hidden; padding: 84px 0 40px; }
.hero::before { content: ""; position: absolute; inset: -40% -20% auto; height: 130%;
  background: radial-gradient(60% 70% at 75% 20%, color-mix(in srgb, var(--teal) 16%, transparent), transparent 70%),
              radial-gradient(45% 55% at 15% 75%, color-mix(in srgb, var(--coral) 9%, transparent), transparent 70%);
  pointer-events: none; }
.hero .wrap { position: relative; display: grid; grid-template-columns: 1.05fr .95fr; gap: 40px; align-items: center; }
.hero h1 { font-size: clamp(34px, 5vw, 52px); line-height: 1.12; letter-spacing: -.02em; margin: 14px 0 18px; }
.hero h1 .accent { color: var(--teal); }
.hero p.lead { font-size: clamp(16px, 2vw, 19px); color: var(--muted); max-width: 34em; margin: 0 0 26px; }
.cta-row { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.cta-note { font-size: 13px; color: var(--muted); margin-top: 12px; }

/* phone mockups */
.phones { position: relative; display: flex; justify-content: center; min-height: 540px; }
.phone {
  width: 252px; border-radius: 40px; padding: 10px; background: var(--ink);
  box-shadow: 0 30px 70px rgba(27, 38, 50, .35);
}
@media (prefers-color-scheme: dark) { .phone { background: #000; box-shadow: 0 30px 70px rgba(0,0,0,.7); } }
.phone img { border-radius: 31px; }
.phones .phone.back { position: absolute; right: 6%; top: 44px; transform: rotate(7deg) scale(.94); opacity: .92; }
.phones .phone.front { position: relative; z-index: 2; transform: rotate(-3deg); margin-right: 22%; }

/* stats */
.stats { padding: 26px 0 8px; }
.stats .wrap { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.stat { background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 20px 12px; text-align: center; }
.stat b { display: block; font-size: clamp(22px, 3vw, 30px); color: var(--teal-deep); letter-spacing: -.01em; }
.stat span { font-size: 13.5px; color: var(--muted); font-weight: 600; }

/* sections */
section.block { padding: 72px 0 8px; }
.kicker { text-align: center; font-size: 13px; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; color: var(--teal-deep); }
section.block h2 { text-align: center; font-size: clamp(26px, 3.6vw, 36px); letter-spacing: -.015em; margin: 10px auto 14px; max-width: 22em; }
.section-lead { text-align: center; color: var(--muted); max-width: 44em; margin: 0 auto 40px; }

/* features */
.grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature { background: var(--card); border: 1px solid var(--line); border-radius: 20px; padding: 24px; transition: transform .18s ease, box-shadow .18s ease; }
.feature:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.feature .ico { width: 46px; height: 46px; display: grid; place-items: center; font-size: 23px;
  border-radius: 14px; background: color-mix(in srgb, var(--teal) 12%, transparent); margin-bottom: 14px; }
.feature h3 { margin: 0 0 6px; font-size: 17.5px; }
.feature p { margin: 0; color: var(--muted); font-size: 15px; }

/* screenshots strip */
.shots { display: flex; justify-content: center; gap: 26px; flex-wrap: wrap; }
.shots .phone { width: 232px; }

/* widget split */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; align-items: center; }
.split .phone { width: 262px; margin: 0 auto; }
.split ul { list-style: none; padding: 0; margin: 18px 0 0; }
.split li { padding-left: 30px; position: relative; margin: 12px 0; color: var(--muted); }
.split li::before { content: "✓"; position: absolute; left: 0; top: 0; color: var(--teal); font-weight: 800; }
.split h2 { text-align: left; margin-left: 0; }
.split .kicker { text-align: left; }

/* tone chips demo */
.tones { display: flex; gap: 8px; flex-wrap: wrap; justify-content: center; margin: 0 0 40px; }
.tone { font-weight: 800; font-size: 14px; padding: 7px 13px; border-radius: 999px; color: #fff; }

/* launch status */
.launch-card {
  display: flex; align-items: center; justify-content: space-between; gap: 28px;
  background: var(--card); border: 1px solid var(--line); border-radius: 24px;
  padding: clamp(26px, 5vw, 46px); box-shadow: var(--shadow);
}
.launch-card .kicker, .launch-card h2 { text-align: left; }
.launch-card h2 { margin: 8px 0; }
.launch-card p { margin: 0; color: var(--muted); }
.launch-card .btn { flex: 0 0 auto; }

/* footer */
footer.site { margin-top: 84px; border-top: 1px solid var(--line); padding: 36px 0 46px; }
footer.site .wrap { display: flex; flex-wrap: wrap; gap: 18px; align-items: center; }
footer.site .links { margin-left: auto; display: flex; gap: 20px; flex-wrap: wrap; }
footer.site a { color: var(--muted); font-size: 14px; }
footer.site .copy { width: 100%; color: var(--muted); font-size: 13px; margin-top: 8px; }

@media (max-width: 900px) {
  .hero .wrap { grid-template-columns: 1fr; text-align: center; }
  .hero p.lead { margin-inline: auto; }
  .cta-row { justify-content: center; }
  .phones { min-height: 480px; margin-top: 10px; }
  .phones .phone.front { margin-right: 18%; }
  .stats .wrap { grid-template-columns: repeat(2, 1fr); }
  .grid3 { grid-template-columns: 1fr; }
  .split { grid-template-columns: 1fr; text-align: center; }
  .split h2, .split .kicker { text-align: center; }
  .split li { text-align: left; }
  .topnav a:not(.btn) { display: none; }
  .launch-card { flex-direction: column; text-align: center; }
  .launch-card .kicker, .launch-card h2 { text-align: center; }
}