:root {
  --bg: #f6f7fb;
  --fg: #111827;
  --muted: #4b5563;
  --accent: #1d4ed8;
  --accent-fg: #ffffff;
  --card: #ffffff;
  --border: #d1d5db;
  --focus: #1d4ed8;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0b1020;
    --fg: #e5e7eb;
    --muted: #b6bfcc;
    --accent: #7dd3fc;
    --accent-fg: #0b1020;
    --card: #131a2e;
    --border: #334155;
    --focus: #7dd3fc;
  }
}

:root[data-theme="dark"] {
  --bg: #0b1020;
  --fg: #e5e7eb;
  --muted: #b6bfcc;
  --accent: #7dd3fc;
  --accent-fg: #0b1020;
  --card: #131a2e;
  --border: #334155;
  --focus: #7dd3fc;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  overflow-wrap: anywhere;
}

main, header, footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px;
}

h1 { font-size: 1.75rem; line-height: 1.25; margin: 24px 0 8px; }
h2 { font-size: 1.2rem; margin: 28px 0 8px; }
p { margin: 8px 0; }
small { color: var(--muted); }

.lang { display: flex; gap: 12px; font-size: 0.9rem; }
.lang a, footer a, main a:not(.button) { color: var(--accent); }

.button {
  display: inline-block;
  padding: 12px 18px;
  margin: 8px 8px 8px 0;
  border-radius: 8px;
  background: var(--accent);
  color: var(--accent-fg);
  text-decoration: none;
  font-weight: 600;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  margin: 12px 0;
}

ol { padding-left: 1.2em; }
li { margin: 6px 0; }

a:focus-visible, .button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

footer { border-top: 1px solid var(--border); margin-top: 32px; font-size: 0.9rem; color: var(--muted); }

@media print {
  .lang, .button, footer nav { display: none; }
  body { background: #fff; color: #000; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}