 margin: 2em 0 0 0; position: relative; }
   .test .c { background: aqua; margin: 3em 0 0 0; height: 1em; }
   .test .d { background: lime; margin: 0; height: 1em; width: 100%; }
   .test .pos { position: absolute; }
   .test .float { float: left; }
   /* control */
   .control div { width: 1em; }
   .control .a { border-top: 1em yellow solid; }
   .control .b { border-top: 2em orange solid; }
   .control .c { border-top: 1em lime solid; }
   .control .d { border-top: 1em aqua solid; }
  </style>
 </head>
 