body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 0;
  background: #f7f9fb;
  color: #333;
}
header, footer {
  background: #3b4b61;
  color: white;
  padding: 1em;
  text-align: center;
}
header nav a, footer a {
  color: white;
  margin: 0 10px;
  text-decoration: none;
}
.btn {
  background: #4a90e2;
  color: white;
  padding: 10px 20px;
  border-radius: 5px;
  text-decoration: none;
}
#editor {
  margin: 20px;
  padding: 10px;
  border: 1px solid #ccc;
  background: white;
  min-height: 400px;
}