* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
}

.header {
  background-color: #f8f8f8;
  padding: 20px;
  text-align: center;
}

.login-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.login-container button {
  margin-bottom: 20px;
}

.main-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.color-display {
  width: 100px;
  height: 100px;
  border: 1px solid #000;
  margin-bottom: 20px;
}