Wordpress rounded corners on widget

Hi everyone,

I've been trying to customize the theme piano-black for wordpress. I wanted to create boxes around the widgets with rounded corners. The problem I'm running into is that the top bit of the box doesn't align with the bottom bit. You can see this in the picture.

Here's my CSS. If someone could tell me what I'm doing wrong I would greatly appreciate it. I've been playing around with the padding and the margins for ages and no matter what I do, it won't budge.

.side-title { margin:0px 0 20px 0; 
font-size:11px; 
text-transform:none; 
text-align:center; 
color:#999; 
font-weight:normal; 
line-height:100%; 
background:url(img/info-box-top.gif) no-repeat left top; 
padding:25px 20px 5px 20px;  
width:232px; 
}
 
.side-box { color:#aaa; 
line-height:160%; 
margin:0 0 50px 30px; 
font-size:11px; 
width:232px; 
background:url(img/info-box-bottom.gif) no-repeat bottom left; 
padding:12px 20px 20px 20px; 
}