互換モードと標準準拠モード

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html lang="ja-JP">
 <head>
 <style type="text/css"><!--
  body { height:100%;  overflow:hidden;}
  form#red { width:100%; height: 100%; background: red;}
  textarea#blue { width: 100%; height: 90%; background: blue;}
 --></style>
 </head>
 <body>
  <form id="red">
   <input><input type=submit><br>
   <textarea id="blue">
   </textarea>
   </form>