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.

As with any shorthand property, individual inherited values are not possible, that is border-radius:0 0 inherit inherit, which would override existing definitions partially. In that case, the individual longhand properties have to be used.

Initial valueas each of the properties of the shorthand:
Applies toall elements; but User Agents are not required to apply to table and inline-table elements when border-collapse is collapse. The behavior on internal table elements is undefined for the moment.. It also applies to ::first-letter.
Inheritedno
Percentagesrefer to the corresponding dimension of the border box
Mediavisual
Computed valueas each of the properties of the shorthand:
Animation typeas each of the properties of the shorthand:
Canonical orderthe unique non-ambiguous order defined by the formal grammar

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 all-corner.png 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 top-left-bottom-right.png 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 top-right-bottom-left.png 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 top-left.png 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 top-right.png 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 bottom-rigth.png 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 bottom-left.png 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 ellipsis. 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 ellipsis, 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

Specification Status Comment
CSS Backgrounds and Borders Module Level 3
The definition of 'border-radius' in that specification.
Candidate Recommendation Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support

41

1 -webkit-

Yes

Yes -webkit-

42 3

1 — 12 -moz-

910.54

51

3 -webkit-

Elliptical borders Yes5 Yes3.5 Yes Yes Yes6
4 values for 4 corners4 Yes Yes Yes Yes5
Percentages Yes7 Yes48 Yes11.595.17
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support2.1 -webkit- ?

Yes

Yes -webkit-

Yes2
Elliptical borders ? ? Yes Yes ? No ?
4 values for 4 corners ? ? Yes Yes ? No ?
Percentages Yes7 ? Yes Yes ? No Yes7

1. Current Chrome and Safari versions ignore border-radius on <select> elements unless -webkit-appearance is overridden to an appropriate value.

2. Prior to Firefox 50, border styles of rounded corners (with border-radius) were always rendered as if border-style was solid. This has been fixed in Firefox 50.

3. To conform to the CSS3 standard, Firefox 4 changes the handling of <percentage> values to match the specification. You can specify an ellipse as a border on an arbitrary sized element with border-radius: 50%;. Firefox 4 also makes rounded corners clip content and images if overflow: visible is not set.

4. In Opera prior to version 11.60, replaced elements with border-radius will not have rounded corners.

5. Prior to Chrome 4, the slash / notation is unsupported. If two values are specified, an elliptical border is drawn on all four corners. -webkit-border-radius: 40px 10px; is equivalent to border-radius: 40px/10px;.

6. Prior to Safari 4.1, the slash / notation is unsupported. If two values are specified, an elliptical border is drawn on all four corners. -webkit-border-radius: 40px 10px; is equivalent to border-radius: 40px/10px;.

7. <percentage> values are not supported in older Chrome and Safari versions (it was fixed in Sepember 2010).

8. <percentage> values are implemented in a non-standard way prior to Firefox 4. Both horizontal and vertical radii were relative to the width of the border box.

9. The implementation of <percentage> values was buggy in Opera prior to 11.50.

 

See also