:root {
  --bg: #F4F4F7;
  --card: #FFFFFF;
  --text: #16161A;
  --text-2: rgba(0, 0, 0, 0.6);
  --border: rgba(0, 0, 0, 0.08);
  --primary: #1E88E5;
  --primary-soft: rgba(30, 136, 229, 0.10);
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0F0F12;
    --card: #1A1A1F;
    --text: #F2F2F5;
    --text-2: rgba(255, 255, 255, 0.64);
    --border: rgba(255, 255, 255, 0.10);
    --primary: #64B5F6;
    --primary-soft: rgba(100, 181, 246, 0.14);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--primary); }

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

header.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  text-decoration: none;
  color: var(--text);
}

/* Icon Play Store vuông tràn viền; bo góc 22% giống cách Play Store hiển thị. */
.brand-mark {
  width: 36px;
  height: 36px;
  border-radius: 22%;
  flex-shrink: 0;
  display: block;
}

.lang {
  font: 12px/1 ui-monospace, "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--card);
  color: var(--text-2);
  text-decoration: none;
}

h1 {
  font-size: 30px;
  line-height: 1.25;
  margin: 0 0 8px;
}

h2 {
  font-size: 19px;
  margin: 36px 0 10px;
}

h3 {
  font-size: 16px;
  margin: 20px 0 6px;
}

p, li { color: var(--text); }

.muted { color: var(--text-2); }

.label {
  font: 11px/1.4 ui-monospace, "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-2);
  margin: 32px 0 8px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 4px 18px;
}

.card > * + * { border-top: 1px solid var(--border); }

.row { padding: 14px 0; }

.row strong { display: block; }

.row span { color: var(--text-2); }

.callout {
  background: var(--primary-soft);
  border-radius: 14px;
  padding: 14px 18px;
  margin: 20px 0;
}

.callout ul { margin: 6px 0 0; padding-left: 20px; }

.button {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  padding: 12px 18px;
  border-radius: 12px;
  margin-top: 8px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}

th, td {
  text-align: left;
  vertical-align: top;
  padding: 10px 8px;
  border-bottom: 1px solid var(--border);
}

th { color: var(--text-2); font-weight: 600; }

.table-wrap { overflow-x: auto; }

footer {
  margin-top: 48px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 14px;
  color: var(--text-2);
}

@media (max-width: 520px) {
  h1 { font-size: 25px; }
  th, td { padding: 8px 4px; }
}

/* ---------- Hướng dẫn sử dụng ---------- */

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 20px 0 8px;
}

.chips a {
  font-size: 14px;
  padding: 7px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--card);
  color: var(--text);
  text-decoration: none;
}

.chips a:hover { border-color: var(--primary); color: var(--primary); }

.action-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(220px, 100%), 1fr));
  gap: 10px;
}

.action {
  display: block;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 12px 14px;
  color: var(--text);
  text-decoration: none;
}

a.action:hover { border-color: var(--primary); }

.action strong { display: flex; align-items: center; gap: 6px; }

.action span { display: block; font-size: 14px; color: var(--text-2); margin-top: 2px; }

.action .state {
  margin-top: 8px;
  font: 11px/1.4 ui-monospace, "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

a.action .state { color: var(--primary); }

.badge {
  font: 600 10px/1 ui-monospace, "SFMono-Regular", Consolas, monospace;
  letter-spacing: 0.06em;
  padding: 4px 6px;
  border-radius: 6px;
  background: var(--primary-soft);
  color: var(--primary);
}

.guide {
  margin-top: 40px;
  padding-top: 8px;
  scroll-margin-top: 16px;
}

.guide-body {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 28px;
  align-items: start;
}

/* Khung điện thoại bao quanh video; video xuất ở 480×1100. */
.phone {
  margin: 0;
  position: sticky;
  top: 16px;
}

.phone img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 480 / 1100;
  border-radius: 28px;
  border: 6px solid #1A1A1F;
  background: #000;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.18);
}

.phone figcaption {
  font-size: 13px;
  color: var(--text-2);
  text-align: center;
  margin-top: 10px;
}

.steps {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 12px 0 0;
}

.steps li {
  counter-increment: step;
  position: relative;
  padding: 0 0 14px 40px;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  font: 600 13px/26px system-ui, sans-serif;
  text-align: center;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  font-size: 14px;
  color: var(--text-2);
  margin: 4px 0 0;
  padding: 0;
  list-style: none;
}

.legend li { display: flex; align-items: center; gap: 8px; color: var(--text-2); }

.dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  flex-shrink: 0;
}

.dot.user { background: #FF8C00; box-shadow: 0 0 0 3px rgba(255, 140, 0, 0.3); }

.dot.auto { background: #22C55E; box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.3); }

@media (max-width: 640px) {
  .guide-body { grid-template-columns: 1fr; }
  .phone { position: static; max-width: 280px; margin: 0 auto; }
}

.result {
  font-weight: 600;
  color: var(--primary);
  margin: 4px 0 0;
}

.top-link { font-size: 14px; margin: 8px 0 0; }

.guide h2 { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }