如何让textarea占满div的宽度？？？
<!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> <title>Ajax留言板</title> <style type="text/css"> #bk { width:800px; border:1px solid red; margin:0 auto; } #lyInput { width:100%; } #txtLy { width:100%; /* 为什么textarea的宽度要宽于bk的宽度，如何让它正好占满bk的宽度？？？ */ height:100px; } #lyList { height:200px; border:1px solid blue; margin:10px 0 0 0; } #btnLy { display:block; } </style></head><body><div id="bk"> <div id="lyInput"> <textarea id="txtLy" rows="6" cols="80"></textarea> <button id="btnLy">留言啦~~~</button> </div> <div id="lyList"> </div></div></body></html>