試試這個， 不知滿足樓主要求否？
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/>
<title>test</title>
<style type="text/css">
.header { width: 100%; background: #567; height: 100px;
} .col1, .col2, .col3 { float: left; width: 80px; background: #DDD; height: 100%; margin-right: 10px; word-wrap:break-word; overflow:hidden; padding-bottom:100%; margin-bottom:-98%; font-size:12px;
} .foot{height:100px; background-color:#ccc;} .middle{overflow:hidden; zoom:1;} </style></head><body><div class="header">header</div><div class="middle">
<div class="col1">111colsdfffffffffffffffffffffffffffffcolsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1fffffff1222</div>
<div class="col2">col2</div>
<div class="col3">333colsdfffffffffffffffffffffffffffffcolsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1fffffff1colsdfffffffffffffffffffffffffffffcolsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1colsdffffffffffffffffffffffffffffffffffff1fffffff1444</div></div><div class="foot">foot</div></body></html>
