* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #f5f7fa;
  color: #243247;
  line-height: 1.7;
}

header {
  background: #14283e;
  color: #fff;
  padding: 24px 8%;
}

header h1 { margin: 0 0 12px; }

nav a {
  color: #d9e8f5;
  margin-right: 22px;
  text-decoration: none;
}

main {
  margin: 65px auto;
  max-width: 900px;
  min-height: 45vh;
  padding: 0 25px;
}

footer {
  border-top: 1px solid #ddd;
  text-align: center;
  padding: 30px;
  color: #64748b;
}