:root {
  --bg: #fbfaf6;
  --surface: #ffffff;
  --text: #1a1c18;
  --muted: #5c6158;
  --primary: #1b5e3a;
  --danger: #c0392b;
  --border: #e3e0d4;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12140f;
    --surface: #1d211a;
    --text: #e3e4dd;
    --muted: #a2a89d;
    --primary: #7fb796;
    --danger: #ef6b5b;
    --border: #2c3128;
  }
}

* { box-sizing: border-box; }

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

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 32px 16px 64px;
}

h1 { font-size: 1.8rem; line-height: 1.25; margin: 0 0 8px; }
h2 { font-size: 1.2rem; margin: 32px 0 8px; }
p, li { color: var(--text); }
.muted { color: var(--muted); font-size: 0.95rem; }
a { color: var(--primary); }

nav { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 32px; font-size: 0.95rem; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  margin-top: 16px;
}

label { display: block; font-weight: 600; margin: 12px 0 4px; }

input {
  width: 100%;
  padding: 10px 12px;
  font: inherit;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}

button {
  margin-top: 20px;
  padding: 12px 18px;
  font: inherit;
  font-weight: 600;
  color: #fff;
  background: var(--danger);
  border: 0;
  border-radius: 8px;
  cursor: pointer;
}

button:disabled { opacity: 0.6; cursor: default; }

.check { display: flex; gap: 8px; align-items: flex-start; margin-top: 16px; font-weight: normal; }
.check input { width: auto; margin-top: 5px; }

#result { margin-top: 16px; font-weight: 600; }
#result.ok { color: var(--primary); }
#result.error { color: var(--danger); }