:root {
  --bg: #f6f7fb;
  --fg: #1f2330;
  --accent: #3b82f6;
  --muted: #6b7280;
  --card: #ffffff;
  --shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.6;
}

header {
  text-align: center;
  padding: 4rem 1rem 2rem;
}

header h1 {
  margin: 0;
  font-size: 3rem;
}

.tagline {
  color: var(--muted);
  margin-top: 0.5rem;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 1rem;
}

.intro {
  background: var(--card);
  border-radius: 12px;
  padding: 2rem;
  box-shadow: var(--shadow);
}

button {
  background: var(--accent);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 1rem;
  transition: opacity 0.2s;
}

button:hover {
  opacity: 0.9;
}

.output {
  margin-top: 1rem;
  color: var(--accent);
  font-weight: 500;
  min-height: 1.5em;
}

footer {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--muted);
  font-size: 0.9rem;
}