CSS border-top-left-radius

The CSS border-top-left-radius property is used when adding rounded corners to your borders. This property allows you to set the border radius on the top-left corner.

The border-top-left-radius property can be used in conjunction with the border property (or another border-related property) in order to set the actual border, however, it can also be used without explicitly setting those properties. For example, if you've set a background color for the element, the background color will be rounded at the corners (even if you don't explictly set a border property).

See border-radius for a shorthand method for setting the border radius across all four sides at once.

Syntax

border-top-left-radius: radius

Or:

border-top-left-radius: horizontal-radius vertical-radius

See below for a more detailed explanation of the accepted values.

Possible Values

Values/Syntax

The possible values for this property are:

[ <length> | <percentage> ]{1,2}

Explanation of the Values

<length>
Specifies the radius using a fixed length, for example, 10px.
<percentage>
Specifies the radius using a percentage value, for example, 10%.

Explanation of the Syntax

You can provide either one or two values:

  • If you provide only one value, it will determine the radius of both the horizontal radius and the vertical radius.
  • If you provide two values, the first value determines the horizontal radius, and the second value determines the vertical radius.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial
Represents the value specified as the property's initial value.
inherit
Represents the computed value of the property on the element's parent.
unset
This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

Basic Property Information

Initial Value
0
Applies To
All elements
Inherited?
No
Media
Visual
Animatable
Yes (see example)

Example Code

Basic CSS

border-top-left-radius: 8px;

Working Example within an HTML Document

<!DOCTYPE html>
<title>Example</title>
<style>
.rounded-border {
  width: 200px;
  padding: 30px;
  border: 1px solid crimson;
  border-top-left-radius: 35px 20px;
}
</style>
<div class="rounded-border">
  This box has a rounded corner.
</div>

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CSS Specifications

Browser Support

The following table provided by Caniuse.com shows the level of browser support for this feature.

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.