:root {
  --bg: #0b1020;
  --panel: #121932;
  --text: #e7eaf3;
  --muted: #9aa3b2;
  --brand: #6aa0ff;
  --border: #1f2745;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: linear-gradient(180deg, #0b1020 0%, #0b1020 60%, #0a0f1d 100%);
}

header {
  padding: 20px;
  border-bottom: 1px solid var(--border);
  background: rgba(18, 25, 50, 0.6);
  backdrop-filter: blur(6px);
  position: sticky;
  top: 0;
}

h1 { margin: 0 0 8px; font-size: 20px; }
h2 { margin: 24px 0 8px; font-size: 16px; }
h3 { margin: 0 0 8px; font-size: 14px; }

nav a {
  color: var(--text);
  text-decoration: none;
  margin-right: 14px;
  padding: 6px 10px;
  border-radius: 6px;
}
nav a[aria-current="page"], nav a:hover {
  background: var(--panel);
}

main {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
}

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

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  padding: 16px;
  border-radius: 10px;
}

button {
  background: var(--brand);
  color: #06122a;
  border: none;
  padding: 8px 12px;
  border-radius: 8px;
  cursor: pointer;
}
button:hover { filter: brightness(1.05); }

code { color: #c4d6ff; }
.output {
  background: #0a0f1d;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  min-height: 44px;
  white-space: pre-wrap;
}

footer {
  border-top: 1px solid var(--border);
  padding: 16px 20px;
  color: var(--muted);
}