soy novato en esto del html y css y la verdad que me he encontrado con un primer gran obstaculo, a ver si alguno me puede ayudar. Paso a comentarle:
Estoy diseñando una página web y necesito crear diferentes bloques con bordes redondeados, todo funciona correctamente en firefox y demas navegadores excepto en IE!!!!

alguien tiene alguna idea de porque ie no interpreta la altura que yo estoy marcandole a esos div???
Aquí les dejo mi código a ver si alguien puede comentarme algo porque no encuentro solución:
<html>
<head>
<style>
body{
background: #686868;
}
.box-rounded,
.box-rounded2{
background:#ffffff;
position:relative;
width:400px;
}
.box-rounded .box-content,
.box-rounded2 .box-content{
padding:12px;
}
.box-rounded .tl,
.box-rounded .tr,
.box-rounded .bl,
.box-rounded .br {
display:block;
height:20px;
position:absolute;
width:20px;
}
.box-rounded2 .tl,
.box-rounded2 .tr,
.box-rounded2 .bl,
.box-rounded2 .br {
display:block;
height:10px;
position:absolute;
width:10px;
}
.box-rounded .tl {
background:transparent url(img/layout/tl.png) no-repeat scroll;
left:0;
top:0;
}
.box-rounded .tr {
background:transparent url(img/layout/tr.png) no-repeat scroll;
right:0;
top:0;
}
.box-rounded .bl {
background:transparent url(img/layout/bl.png) no-repeat scroll;
bottom:0;
left:0;
}
.box-rounded .br {
background:transparent url(img/layout/br.png) no-repeat scroll;
bottom:0;
right:0;
}
.box-rounded2 .tl {
background:transparent url(img/layout/tl2.png) no-repeat scroll;
left:0;
top:0;
}
.box-rounded2 .tr {
background:transparent url(img/layout/tr2.png) no-repeat scroll;
right:0;
top:0;
}
.box-rounded2 .bl {
background:transparent url(img/layout/bl2.png) no-repeat scroll;
bottom:0;
left:0;
}
.box-rounded2 .br {
background:transparent url(img/layout/br2.png) no-repeat scroll;
bottom:0;
right:0;
}
.clear{
margin-bottom: 10px;
clear: both;
}
</style>
</head>
<body>
<div class="box-rounded2">
<span class="tl"></span>
<span class="tr"></span>
<span class="bl"></span>
<span class="br"></span>
<div class="box-content">
<h2>Smart, Round Corners?</h2>
<p>This is some div text content. To watch the rounded corners on this box move dynamically, use your browser’s functionality to enlarge this text.</p>
<p>It might not be an original solution, but it is simple, effective, and lightweight. Smart Corners are what I’d call smart.</p>
<p>Oh, yeah, I like it! So round, so smart, so simple and easy

</div>
</div>
<div class="clear"> </div>
<div class="box-rounded">
<span class="tl"></span>
<span class="tr"></span>
<span class="bl"></span>
<span class="br"></span>
<div class="box-content">
<h2>Smart, Round Corners?</h2>
<p>This is some div text content. To watch the rounded corners on this box move dynamically, use your browser’s functionality to enlarge this text.</p>
<p>It might not be an original solution, but it is simple, effective, and lightweight. Smart Corners are what I’d call smart.</p>
<p>Oh, yeah, I like it! So round, so smart, so simple and easy

</div>
<div class="clear"></div>
</div>
</body>
</html>