我想要箭头结束位置的红色框。jsbin
<div id="wrapper">
<div id="blue"></div>
<div id="yellow1">y</div>
<div id="yellow2">y</div>
<div id="red"></div>
</div>
body{width:800px;}
#wrapper{position:relative;}
#blue{
float:left;
height:225px;
width:520px;
background:blue;
}
#yellow1,#yellow2{
position:relative;
width:250px;
height:200px;
margin:10px 0 20px 540px;
background:yellow;}
/*Not working*/
#red{
background:red;
position:absolute;
height:200px;
width:520px;
top:200;
}