html, body {
  margin: 0;
  padding: 0;
  border: 0;
}
body { background-color: #ccc; /* change the color to your background color */ }
#main {
  width: 80%;
  max-width: 1000px;
  background-color:#fff;
  border: solid black medium; /* remove if you don't want a border */
  margin: 2em auto;
  padding: 1em;
}