This is the styling for this div:
margin: 0.2in auto;
color: #fff;
width: 300px;
height:500px;
padding: 20px;
text-align: left;
background-color: #33F;
border-radius:20px 0;
-webkit-border-bottom-right-radius: 20px;
-webkit-border-top-left-radius: 20px;
-moz-border-radius: 20px 0;
You don't have to round all the corners of a box. There are some constraints,
mostly common sense, about box styling.
For example, it makes no sense to style a box
with rounded top corners, a top border but no side border; and the results
can be relied upon to look odd!
You can of course have rounded top corners with
a border to left, top and right (but none on the bottom).
That is how the tabs are styled.