:root {
  --bg: #ffffff;
  --text: #111111;
  --card: #f2f2f2;
  --btn: #ff3b3b;
}

[data-theme="dark"] {
  --bg: #0f0f0f;
  --text: #ffffff;
  --card: #1c1c1c;
}

* {
  box-sizing: border-box;
  font-family: system-ui, sans-serif;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.app {
  background: var(--card);
  padding: 24px;
  border-radius: 16px;
  width: min(360px, 92vw);
  text-align: center;
}

.timer {
  font-size: 56px;
  font-weight: bold;
  margin: 16px 0;
}

button {
  padding: 10px 14px;
  border: none;
  border-radius: 8px;
  background: var(--btn);
  color: white;
  cursor: pointer;
}