border-start-start-radius

The border-start-start-radius CSS property defines a logical border radius on an element, which maps to a physical border radius that depends on the element's writing-mode, direction, and text-orientation. This is useful when building styles to work regardless of the text orientation and writing mode.

/* <length> values */
/* With one value the corner will be a circle */
border-start-start-radius: 10px;  
border-start-start-radius: 1em;   

/* With two values the corner will be an ellipse */
border-start-start-radius: 1em 2em;

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

For instance, in a horizontal-tb writing mode this property corresponds to the border-top-left-radius property.

Syntax

Values

<length-percentage>

Denotes the size of the circle radius or the semi-major and semi-minor axes of the ellipse. As absolute length it can be expressed in any unit allowed by the CSS <length> data type. 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.

Formal definition

Formal syntax

<length-percentage>{1,2}
where 
<length-percentage> = <length> | <percentage>

Examples

Border radius with vertical text

HTML

<div>
  <p class="exampleText">Example</p>
</div>

CSS

div {
  background-color: rebeccapurple;
  width: 120px;
  height: 120px;
  border-start-start-radius: 10px;
}

.exampleText {
  writing-mode: vertical-rl;
  padding: 10px;
  background-color: #fff;
  border-start-start-radius: 10px;
}

Results

Specifications

Browser compatibility

See also

• The mapped physical property: border-top-left-radius
• writing-mode, direction, text-orientation