rx CSS property

The rx CSS property defines the x-axis, or horizontal, radius of an SVG <ellipse> and the horizontal curve of the corners of an SVG <rect> rectangle. If present, it overrides the shape's rx attribute.

Syntax

/* Initial value */
rx: auto;

/* Length and percentage values */
rx: 20px;
rx: 20%;

/* Global values */
rx: inherit;
rx: initial;
rx: revert;
rx: revert-layer;
rx: unset;

Values

The <length>, <percentage>, or auto keyword value denotes the horizontal radius of ellipses and the horizontal border-radius of rectangles.

<length>

Absolute or relative lengths can be expressed in any unit allowed by the CSS <length> data type. Negative values are invalid.

<percentage>

Percentages refer to the width of the current SVG viewport. The used value for a <rect> is never more than 50% of the width of the rectangle.

auto

When set or defaulting to auto, the rx value equals the absolute length value used for ry. If both rx and ry have a computed value of auto, the used value is 0.

Formal definition

Formal syntax

rx = 
  <length-percentage>  |
  auto                 

<length-percentage> = 
  <length>      |
  <percentage>  

Examples

Creating rounded corners

This example demonstrates creating rectangles with rounded corners by applying the rx property to SVG <rect> elements.

HTML

We include an SVG image with four <rect> elements; all the rectangles are the same except for their x attribute value, which positions them along the x-axis.

<svg xmlns="http://www.w3.org/2000/svg">
  <rect width="50" height="120" y="5" x="5" />
  <rect width="50" height="120" y="5" x="60" />
  <rect width="50" height="120" y="5" x="115" />
  <rect width="50" height="120" y="5" x="170" />
  <rect width="50" height="120" y="5" x="225" />
</svg>

CSS

With CSS, we set an rx value on four of the rectangles:

svg {
  border: 1px solid;
}

rect:nth-of-type(2) {
  rx: 10px;
  fill: red;
}

rect:nth-of-type(3) {
  rx: 2em;
  fill: blue;
}

rect:nth-of-type(4) {
  rx: 5%;
  fill: orange;
}

rect:nth-of-type(5) {
  rx: 80%;
  fill: green;
}

Results

The first rectangle defaults to auto; as all the ry values in this example also default to auto, the used value of rx is 0. The red and blue rectangles have 10px and 2em rounded corners, respectively. As the SVG viewport defaults to 300px by 150px, the orange rectangle's 5% value creates a 15px radius. The green rectangle has rx: 80% set. However, as the value of rx is never more than 50% of the width of the rectangle, the effect is as if rx: 50%; ry: 50% was set.

Defining the horizontal radius of an ellipse

This basic <ellipse> example demonstrates the CSS rx property taking precedence over an SVG rx attribute to define the shape's horizontal radius.

HTML

We include two identical <ellipse> elements in an SVG; each with the rx attribute set to 20.

<svg xmlns="http://www.w3.org/2000/svg">
  <ellipse cx="80" cy="50" rx="20" ry="40" />
  <ellipse cx="80" cy="50" rx="20" ry="40" />
</svg>

CSS

We only style the first ellipse, letting its twin use default user agent styles (with fill defaulting to black). The geometric rx property overrides the value of the SVG rx attribute. We also set the fill and stroke properties to differentiate the styled shape from its twin.

svg {
  border: 1px solid;
}

ellipse:first-of-type {
  rx: 80px;
  fill: magenta;
  stroke: rebeccapurple;
}

Results

The styled ellipse's horizontal radius is 80px, as defined in the CSS rx property value. The unstyled ellipse's horizontal radius is 20px, which was defined by the rx attribute.

Ellipse horizontal radius percentage values

This example demonstrates using percentage values for rx.

HTML

We use the same markup as the previous example.

<svg xmlns="http://www.w3.org/2000/svg">
  <ellipse cx="80" cy="50" rx="20" ry="40" />
  <ellipse cx="80" cy="50" rx="20" ry="40" />
</svg>

CSS

The CSS is similar to the previous example, with the only difference being the rx property value; in this case, we use a percentage value.

svg {
  border: 1px solid;
}

ellipse:first-of-type {
  rx: 30%;
  fill: magenta;
  stroke: rebeccapurple;
}

Results

When using percentage values for rx, the values are relative to the width of the SVG viewport. Here, the size of the styled ellipse horizontal radius is 30% of the width of the current SVG viewport. As the width defaulted to 300px, the rx value is 90px.

Specifications

• Scalable Vector Graphics (SVG) 2

See also

• Geometry properties: rx, cx, cy, r, ry, x, y, width, height
• fill
• stroke
• paint-order
• border-radius shorthand property
• radial-gradient
• <basic-shape> data type
• SVG rx attribute