border-radius - CSS: Cascading Style Sheets 编辑

The border-radius CSS property rounds the corners of an element's outer border edge. You can set a single radius to make circular corners, or two radii to make elliptical corners.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

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.

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

Note: As with any shorthand property, individual sub-properties cannot inherit, such as in border-radius:0 0 inherit inherit, which would partially override existing definitions. Instead, the individual longhand properties have to be used.

Constituent properties

This property is a shorthand for the following CSS properties:

• border-bottom-left-radius
• border-bottom-right-radius
• border-top-left-radius
• border-top-right-radius

Syntax

/* 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 / 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;

/* Global values */
border-radius: inherit;
border-radius: initial;
border-radius: unset;

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 "/" and 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.

<length>

Denotes the size of the circle radius, or the semi-major and semi-minor axes of the ellipse, using length values. 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 definition

Initial value	as each of the properties of the shorthand: border-top-left-radius: 0 border-top-right-radius: 0 border-bottom-right-radius: 0 border-bottom-left-radius: 0
Applies to	all 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.
Inherited	no
Percentages	refer to the corresponding dimension of the border box
Computed value	as each of the properties of the shorthand: border-bottom-left-radius: two absolute <length>s or <percentage>s border-bottom-right-radius: two absolute <length>s or <percentage>s border-top-left-radius: two absolute <length>s or <percentage>s border-top-right-radius: two absolute <length>s or <percentage>s
Animation type	as each of the properties of the shorthand: border-top-left-radius: a length, percentage or calc(); border-top-right-radius: a length, percentage or calc(); border-bottom-right-radius: a length, percentage or calc(); border-bottom-left-radius: a length, percentage or calc();

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

BCD tables only load in the browser

See also

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