body {
  background-color: #f7f8fa;
}

header {
  background-color: #4A90E2;
}

h1, h2, h3, h4 {
  color: #4A90E2;
}

button {
  transition: background-color 0.3s ease;
}

footer {
  background-color: #7F8C8D;
}