:root {
  --bg: #f7f6fb;
  --surface: #ffffff;
  --surface-wash: #efeafd;
  --text: #18132a;
  --muted: #5a5373;
  --border: #e3ddf4;
  --brand: #5b2be0;
  --brand-dark: #421cb3;
  --accent-badge: #ede6ff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #100d1c;
    --surface: #1a152c;
    --surface-wash: #261d42;
    --text: #f5f3fc;
    --muted: #b4accf;
    --border: #30274f;
    --brand: #9a75ff;
    --brand-dark: #b59aff;
    --accent-badge: #2a204a;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 24px 20px 64px;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 20px;
  margin-bottom: 28px;
  border-bottom: 1px solid var(--border);
}

.brand-link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.15rem;
}

.brand-logo {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: block;
  flex-shrink: 0;
}

.hero-brand {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 14px;
}

.hero-logo {
  width: 68px;
  height: 68px;
  border-radius: 16px;
  display: block;
  flex-shrink: 0;
}

.hero-brand .badge {
  margin-bottom: 0;
}

.nav-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
}

.nav-row a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.94rem;
  font-weight: 500;
}

.nav-row a:hover,
.nav-row a[aria-current="page"] {
  color: var(--brand);
}

.lang-switch {
  display: inline-flex;
  background: var(--surface-wash);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px;
  gap: 2px;
}

.lang-btn {
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 5px 11px;
  border-radius: 999px;
  cursor: pointer;
}

.lang-btn.active {
  background: var(--brand);
  color: #ffffff;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 28px 26px;
  margin-bottom: 22px;
  box-shadow: 0 2px 10px rgba(18, 12, 40, 0.04);
}

.hero {
  background: radial-gradient(circle at top left, var(--surface-wash), var(--surface) 70%);
}

.badge {
  display: inline-block;
  background: var(--accent-badge);
  color: var(--brand);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 12px;
}

h1 {
  margin: 0 0 10px;
  font-size: 1.95rem;
  line-height: 1.25;
}

h2 {
  margin: 22px 0 10px;
  font-size: 1.25rem;
}

h2:first-child {
  margin-top: 0;
}

p, li {
  color: var(--text);
  font-size: 0.98rem;
}

.muted {
  color: var(--muted);
  font-size: 0.9rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 20px 0;
}

.feature-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
}

.feature-box h3 {
  margin: 0 0 6px;
  font-size: 1.02rem;
}

.callout {
  background: var(--surface-wash);
  border-left: 4px solid var(--brand);
  padding: 14px 18px;
  border-radius: 10px;
  margin: 16px 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0;
  font-size: 0.92rem;
}

th, td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

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

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.86em;
  background: var(--surface-wash);
  padding: 2px 6px;
  border-radius: 5px;
}

.site-footer {
  margin-top: 36px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  font-size: 0.86rem;
  color: var(--muted);
}

.site-footer a {
  color: var(--brand);
  text-decoration: none;
}

[data-lang] {
  display: none;
}

html[lang="vi"] [data-lang="vi"],
html[lang="en"] [data-lang="en"] {
  display: block;
}

html[lang="vi"] span[data-lang="vi"],
html[lang="en"] span[data-lang="en"] {
  display: inline;
}

html[lang="vi"] .badge[data-lang="vi"],
html[lang="en"] .badge[data-lang="en"] {
  display: inline-block;
}