* {
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
  color: #333;
}

header {
  background: #222;
  color: #fff;
  padding: 2rem 1rem;
  text-align: center;
}

main {
  max-width: 900px;
  margin: auto;
  padding: 2rem 1rem;
  background: #fff;
}

h1, h2, h3 {
  margin-top: 1rem;
}

ul {
  padding-left: 1.5rem;
}

blockquote {
  background-color: #eef;
  border-left: 5px solid #77f;
  margin: 1rem 0;
  padding: 1rem;
  font-style: italic;
}

@media (max-width: 600px) {
  header h1 {
    font-size: 1.8rem;
  }

  main {
    padding: 1rem;
  }
}