MediaWiki:Monobook.css

 /* edit this file to customize the monobook skin for the entire site */
 
 h1.firstHeading {
   margin-top: 20px;
 }

 /* only normal articles have white background - test */
 #content {
   background: #F5FAFF;
 }
 .ns-0 #content {
   background: white;
 }