html, body {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100%;
  background: #f5f5f7;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

main {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
}

h1 {
  font-size: 2rem;
  color: #1d1d1f;
}

#big-red-button {
  font-size: 1.5rem;
  font-weight: 600;
  color: #fff;
  background: #d32f2f;
  border: none;
  border-radius: 12px;
  padding: 1.25rem 3rem;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(211, 47, 47, 0.4);
  transition: background 0.15s ease, transform 0.1s ease;
}

#big-red-button:hover {
  background: #b71c1c;
}

#big-red-button:active {
  transform: scale(0.97);
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.875rem;
  color: #6e6e73;
}