:root {
  --bg: #0f172a;
  --card: #111827;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --accent: #2563eb;
  --accent-2: #334155;
  --shadow: rgba(2, 6, 23, 0.6);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  background: linear-gradient(180deg, #0b1020, var(--bg));
  color: var(--text);
}

.site-header {
  text-align: center;
  padding: 32px 16px 8px;
}

.site-header h1 {
  margin: 0;
  font-size: 2rem;
  letter-spacing: 0.5px;
}

.tagline {
  margin: 6px 0 0;
  color: var(--muted);
}

.container {
  max-width: 980px;
  margin: 0 auto;
  padding: 16px;
  display: grid;
  gap: 16px;
}

@media (min-width: 768px) {
  .container {
    grid-template-columns: repeat(3, 1fr);
  }
}

.card {
  background: linear-gradient(180deg, #0f172a, var(--card));
  border: 1px solid #1f2937;
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 10px 30px var(--shadow);
}

.card h2 { margin-top: 0; }

.timer-display {
  font-variant-numeric: tabular-nums;
  font-size: 3rem;
  text-align: center;
  padding: 12px 0 4px;
  letter-spacing: 1px;
}

.button-row, .input-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 8px;
}

button {
  appearance: none;
  border: 1px solid #1e293b;
  background: var(--accent);
  color: white;
  padding: 10px 14px;
  border-radius: 12px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.25);
}
button.secondary {
  background: var(--accent-2);
  color: var(--text);
}

button:active { transform: translateY(1px); }

label { display: flex; flex-direction: column; font-size: 0.9rem; color: var(--muted); }

input[type="number"], input[type="text"] {
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid #1f2937;
  background: #0b1222;
  color: var(--text);
  min-width: 0;
}

.result {
  margin-top: 8px;
  padding: 12px;
  border-radius: 12px;
  background: #0b1222;
  border: 1px solid #1f2937;
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
}

.hint {
  margin-top: 6px;
  color: var(--muted);
  font-size: 0.85rem;
}

.site-footer {
  text-align: center;
  padding: 24px 16px 40px;
  color: var(--muted);
}