radial-gradient()

The radial-gradient() CSS function creates an image consisting of a progressive transition between two or more colors that radiate from an origin. Its shape may be a circle or an ellipse. The function's result is an object of the <gradient> data type, which is a special kind of <image>.

/* A gradient at the center of its container,
   starting red, changing to blue, and finishing green */
radial-gradient(circle at center, red 0, blue, green 100%)

As with any gradient, a radial gradient has no intrinsic dimensions; i.e., it has no natural or preferred size, nor a preferred ratio. Its concrete size will match the size of the element it applies to.

Composition of a radial gradient

A radial gradient is defined by a center point, an ending shape, and two or more color-stop points.

To create a smooth gradient, the radial-gradient() function draws a series of concentric shapes radiating out from the center to the ending shape (and potentially beyond). The ending shape may be either a circle or an ellipse.

Color-stop points are positioned on a virtual gradient ray that extends horizontally from the center towards the right. Percentage-based color-stop positions are relative to the intersection between the ending shape and this gradient ray, which represents 100%. Each shape is a single color determined by the color on the gradient ray it intersects.

Syntax

Values

<position>

The position of the gradient, interpreted in the same way as background-position or transform-origin. If unspecified, it defaults to center.

<shape>

The gradient's shape. The value can be circle (meaning that the gradient's shape is a circle with constant radius) or ellipse (meaning that the shape is an axis-aligned ellipse). If unspecified, it defaults to ellipse.

<extent-keyword>

A keyword describing how big the ending shape must be. The possible keywords are:

Keyword	Description
closest-side	The gradient's ending shape meets the side of the box closest to its center (for circles) or meets both the vertical and horizontal sides closest to the center (for ellipses).
closest-corner	The gradient's ending shape is sized so that it exactly meets the closest corner of the box from its center.
farthest-side	Similar to closest-side, except the ending shape is sized to meet the side of the box farthest from its center (or vertical and horizontal sides).
farthest-corner	The gradient's ending shape is sized so that it exactly meets the farthest corner of the box from its center.

Note: Early implementations of this function included other keywords (cover and contain) as synonyms of the standard farthest-corner and closest-side, respectively. Use the standard keywords only, as some implementations have already dropped those older variants.

<color-stop>

A color-stop's <color> value, followed by an optional stop position (either a <percentage> or a <length> along the gradient's axis). A percentage of 0%, or a length of 0, represents the center of the gradient; the value 100% represents the intersection of the ending shape with the virtual gradient ray. Percentage values in between are linearly positioned on the gradient ray.

Formal syntax

radial-gradient(
  [ [ circle || <length> ]                         [ at <position> ]? , |
    [ ellipse || [ <length> | <percentage> ]{2} ]  [ at <position> ]? , |
    [ [ circle | ellipse ] || <extent-keyword> ]   [ at <position> ]? , |
    at <position> ,
  ]?
  <color-stop> [ , <color-stop> ]+
)
where <extent-keyword> = closest-corner | closest-side | farthest-corner | farthest-side
  and <color-stop>     = <color> [ <percentage> | <length> ]? 

Examples

Simple gradient

.radial-gradient {
  background-image: radial-gradient(cyan 0%, transparent 20%, salmon 40%);
} 

Non-centered gradient

.radial-gradient {
  background-image: radial-gradient(farthest-corner at 40px 40px,
      #f35 0%, #43e 100%);
}

Specifications

Browser compatibility

[1] Firefox 3.6 implemented, prefixed, an early syntax. Before Firefox 36, Gecko didn't apply gradient on the pre-multiplied color space, leading to shade of grey unexpectedly appearing when used with transparency. Since Firefox 42, the prefixed version of gradients can be disabled by setting layout.css.prefixes.gradients to false.

[2] Webkit implemented, prefixed, an early syntax. WebKit since 528 supports the legacy -webkit-gradient(radial,…) function. See also their current support for radial gradients.

[3] Internet Explorer 5.5 through 9.0 supports proprietary filter: progid:DXImageTransform.Microsoft.Gradient() filter.

[4] In addition to the unprefixed support, Gecko 44.0 (Firefox 44.0 / Thunderbird 44.0 / SeaMonkey 2.41) added support for a -webkit prefixed version of the function for web compatibility reasons behind the preference layout.css.prefixes.webkit, defaulting to false. Since Gecko 49.0 (Firefox 49.0 / Thunderbird 49.0 / SeaMonkey 2.46) the preference defaults to true.

Quantum CSS notes

• Gecko has a long-standing bug whereby radial gradient values like radial-gradient(circle gold,red) will work, even though they shouldn't because of the missing comma between circle and gold (bug 1383323). Firefox's new parallel CSS engine (also known as Quantum CSS or Stylo, planned for release in Firefox 57) fixes this bug.
• Also in Gecko, calc() expressions are rejected — causing the value to be invalid — when used as the radius component of a radial-gradient() function (bug 1376019). Firefox's new parallel CSS engine (also known as Quantum CSS or Stylo, planned for release in Firefox 57) fixes this.

See also

• Using CSS gradients
• Other gradient functions: repeating-radial-gradient(), linear-gradient(), repeating-linear-gradient()
• <image>