body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

header {
  padding: 24px;
  border-bottom: 1px solid #ddd;
}

main {
  max-width: 900px;
  margin: 40px auto;
  padding: 20px;
}

h1, h2 {
  margin-top: 0;
}