border-radius

The border-radius CSS property allows Web authors to define how rounded border corners are. You can specify a single radius to make circular corners, or two radii, to make elliptical corners.

/* The syntax of the first radius allows one to four values */
/* Radius is set for all 4 sides */
border-radius: 10px;

/* top-left-and-bottom-right | top-right-and-bottom-left */
border-radius: 10px 5%;

/* top-left | top-right-and-bottom-left | bottom-right */
border-radius: 2px 4px 2px;

/* top-left | top-right | bottom-right | bottom-left */
border-radius: 1px 0 3px 4px;

/* The syntax of the second radius allows one to four values */
/* (first radius values) / radius */
border-radius: 10px 5% / 20px;

/* (first radius values) / top-left-and-bottom-right | top-right-and-bottom-left */
border-radius: 10px 5% / 20px 30px;

/* (first radius values) / top-left | top-right-and-bottom-left | bottom-right */
border-radius: 10px 5px 2em / 20px 25px 30%;

/* (first radius values) / top-left | top-right | bottom-right | bottom-left */
border-radius: 10px 5% / 20px 25em 30px 35em;

border-radius: inherit;

The radius applies to the whole background, even if the element has no border; the exact position of the clipping is defined by the background-clip property.

This property is a shorthand to set the four properties border-top-left-radius, border-top-right-radius, border-bottom-right-radius and border-bottom-left-radius.

The border-radius property does not apply to table elements when border-collapse is collapse.

Syntax

The border-radius property is specified as:

• one, two, three, or four <length> or <percentage> values. This is used to set a single radius for the corners.
• followed optionally by "/" followed by one, two, three, or four <length> or <percentage> values. This is used to set an additional radius, so you can have elliptical corners.

Values

radius		Is a <length> or a <percentage> denoting a radius to use for the border in each corner of the border. It is used only in the one-value syntax.
top-left-and-bottom-right		Is a <length> or a <percentage> denoting a radius to use for the border in the top-left and bottom-right corners of the element's box. It is used only in the two-value syntax.
top-right-and-bottom-left		Is a <length> or a <percentage> denoting a radius to use for the border in the top-right and bottom-left corners of the element's box. It is used only in the two- and three-value syntaxes.
top-left		Is a <length> or a <percentage> denoting a radius to use for the border in the top-left corner of the element's box. It is used only in the three- and four-value syntaxes.
top-right		Is a <length> or a <percentage> denoting a radius to use for the border in the top-right corner of the element's box. It is used only in the four-value syntax.
bottom-right		Is a <length> or a <percentage> denoting a radius to use for the border in the bottom-right corner of the element's box. It is used only in the three- and four-value syntaxes.
bottom-left		Is a <length> or a <percentage> denoting a radius to use for the border in the bottom-left corner of the element's box. It is used only in the four-value syntax.
inherit		Is a keyword indicating that all four values are inherited from their parent's element calculated value.

<length>

Denotes the size of the circle radius or the semi-major and semi-minor axes of the ellipse. It can be expressed in any unit allowed by the CSS <length> data types. Negative values are invalid.

<percentage>

Denotes the size of the circle radius, or the semi-major and semi-minor axes of the ellipse, using percentage values. Percentages for the horizontal axis refer to the width of the box, percentages for the vertical axis refer to the height of the box. Negative values are invalid.

For example:

border-radius: 1em/5em;

/* is equivalent to */

border-top-left-radius:     1em 5em;
border-top-right-radius:    1em 5em;
border-bottom-right-radius: 1em 5em;
border-bottom-left-radius:  1em 5em;

border-radius: 4px 3px 6px / 2px 4px;

/* is equivalent to: */

border-top-left-radius:     4px 2px;
border-top-right-radius:    3px 4px;
border-bottom-right-radius: 6px 2px;
border-bottom-left-radius:  3px 4px;

Formal syntax

<length-percentage>{1,4} [ / <length-percentage>{1,4} ]?
where 
<length-percentage> = <length> | <percentage>

Examples

  border: solid 10px;
  /* the border will curve into a 'D' */  
  border-radius: 10px 40px 40px 10px;
  

  border: groove 1em red;  
  border-radius: 2em;

  background: gold;
  border: ridge gold;
  border-radius: 13em/3em; 

  border: none;
  border-radius: 40px 10px;  

  border: none;
  border-radius: 50%; 

  border: dotted;
  border-width: 10px 4px;
  border-radius: 10px 40px;

  border: dashed;
  border-width: 2px 4px;
  border-radius: 40px;

Live Samples

Sample 1 : http://jsfiddle.net/Tripad/qnGKj/2/

Sample 2 : http://jsfiddle.net/Tripad/qnGKj/3/

Sample 3 : http://jsfiddle.net/Tripad/qnGKj/4/

Sample 4 : http://jsfiddle.net/Tripad/qnGKj/5/

Sample 5 : http://jsfiddle.net/Tripad/qnGKj/6/

Specifications

Browser compatibility

See also

• Border-radius-related CSS properties: border-top-left-radius, border-top-right-radius, border-bottom-right-radius, border-bottom-left-radius