:root {
  --bg-light: #ffffff;
  --text-light: #1a1a1a;

  --bg-dark: #1e1e1e;
  --text-dark: #f5f5f5;
}

body.light {
  background-color: var(--bg-light);
  color: var(--text-light);
}
body.dark {
  background-color: var(--bg-dark);
  color: var(--text-dark);
}
body {
  margin: 0;
  font-family: Calibri;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

button {
  margin-top: 20px;
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
  border: none;
  border-radius: 6px;
  background-color: #999;
}