Rotated square repeating background

style.scss

@import "compass";
$col1: rgba(0,0,0,0);
$col2: #000;

body {
  @include background (
    linear-gradient(65deg, #F00 23%, $col1 10%),
    linear-gradient(155deg, #F00 23%, $col1 10%),
    linear-gradient(245deg, #F00 23%, rgba(0,0,0,0) 10%),
    linear-gradient(335deg, #F00 23%, $col1 10%),
    $col2
    );
  background-size: 50px 50px;
}