:root {
  --bg: #f5f7fb;
  --text: #1f2a3d;
  --card: #ffffff;
  --accent: #2244cc;
}

body[data-theme='night'] {
  --bg: #10131a;
  --text: #eef2ff;
  --card: #1b2230;
  --accent: #92a8ff;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, Arial, sans-serif;
}

.card {
  background: var(--card);
  border-radius: 14px;
  padding: 2rem;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.12);
  width: min(92vw, 520px);
}

button {
  border: 0;
  background: var(--accent);
  color: white;
  border-radius: 10px;
  padding: 0.65rem 1rem;
  cursor: pointer;
}