Border-radius-create rounded corners with CSS

The CSS3 border-radius property allows web developers to easily utilise rounder corners in their design elements, without the need for corner images or the use of multiple div tags, and is perhaps one of the most talked about aspects of CSS3.

Since first being announced in 2005 the boder-radius property has come to enjoy widespread browser support (although with some discrepancies) and, with relative ease of use, web developers have been quick to make the most of this emerging technology.

The code for this example is, in theory, quite simple:

#example1 {
border-radius: 15px;
}

However, for the moment, you’ll also need to use the -moz- prefix to support Firefox (see the browser support section of this article for further details):

#example1 {
-moz-border-radius: 15px;
border-radius: 15px;
}

How it Works

Rounder corners can be created independently using the four individual border-*-radius properties (border-bottom-left-radius, border-top-left-radius, etc.) or for all four corners simultaneously using the border-radius shorthand property.

We will firstly deal with the syntax for the individual border-*-radius properties before looking at how the border-radius shorthand property works.
border-bottom-left-radius, border-bottom-right-radius, border-top-left-radius, border-top-right-radius

The border-*-radius properties can each accept either one or two values, expressed as a length or a percentage (percentages refer to the corresponding dimensions of the border box).
The Syntax:
border-*-*-radius: [ | <%> ] [ | <%> ]?

Examples:
border-top-left-radius: 10px 5px;
border-bottom-right-radius: 10% 5%;
border-top-right-radius: 10px;