CSS border-top-left-radius Rounding Corners for Better Design

Creating Rounded Corners with border-top-left-radius

The border-top-left-radius property in CSS lets you round the top-left corner of an element. This property is useful for designing buttons, cards, and other UI elements with smooth edges.

Basic Usage

Example

HTML

<div></div>

CSS

div {
  border-top-left-radius: 40px;
  background-color: lightgreen;
  border: solid 1px black;
  width: 100px;
  height: 100px;
}

In this example, the border-top-left-radius property is set to 40px, creating a circular arc at the top-left corner of the div element. The background color is light green, and a black border is applied for visibility.

Arc of an Ellipse

You can create an elliptical corner by using two different length values. The first value is for the horizontal radius, and the second is for the vertical radius.

Example

HTML

<div></div>

CSS

div {
  border-top-left-radius: 40px 20px;
  background-color: lightgreen;
  border: solid 1px black;
  width: 100px;
  height: 100px;
}

In this example, border-top-left-radius: 40px 20px; creates an elliptical arc at the top-left corner. The first value (40px) is the horizontal radius, and the second value (20px) is the vertical radius.

Using Percentage Values

You can use percentage values to make the radius relative to the element’s dimensions. This approach is particularly useful for responsive designs.

Example

HTML

<div></div>

CSS

div {
  border-top-left-radius: 40%;
  background-color: lightgreen;
  border: solid 1px black;
  width: 100px;
  height: 100px;
}

In this example, border-top-left-radius: 40%; creates a circular arc at the top-left corner. The radius is 40% of the element’s width and height.

Non-Square Elements

For non-square elements, using percentage values creates an elliptical arc relative to the element’s dimensions.

Example

HTML

<div></div>

CSS

div {
  border-top-left-radius: 40%;
  background-color: lightgreen;
  border: solid 1px black;
  width: 200px;
  height: 100px;
}

In this example, border-top-left-radius: 40%; creates an elliptical arc at the top-left corner. The horizontal radius is 40% of the element’s width (200px), and the vertical radius is 40% of the element’s height (100px).

Combining with Other Border Properties

You can combine border-top-left-radius with other border properties to create visually appealing designs.

Example

.custom-border {
  border-top-left-radius: 20px;
  border-style: dashed;
  border-width: 3px;
  border-color: darkblue;
  background-color: lightyellow;
  width: 150px;
  height: 150px;
}

Formal Syntax

The formal syntax of border-top-left-radius outlines the structure and possible values for defining the curvature of the top-left corner.

Syntax

border-top-left-radius: <length-percentage>[{1,2}];

Length-Percentage

• Length-Percentage: <length> | <percentage>
  • The value can be a length (e.g., px, em, rem) or a percentage.

Curly Braces

• Curly Braces: {1,2}
  • One value defines the radius of a circle; two values define the horizontal and vertical radii of an ellipse.

Examples

• Single Value: Specifies the radius of a circle.

  border-top-left-radius: 3px;

• Two Values: Specifies the horizontal and vertical radii of an ellipse.

  border-top-left-radius: 0.5em 1em;

Global Values

• Global Values: inherit, initial, revert, revert-layer, unset

  border-top-left-radius: inherit;
  border-top-left-radius: initial;
  border-top-left-radius: revert;
  border-top-left-radius: revert-layer;
  border-top-left-radius: unset;

Browser Compatibility

The border-top-left-radius property is widely supported across modern browsers, including:

• Chrome: Supported since version 4.0.
• Edge: Supported since version 12.0.
• Firefox: Supported since version 4.0.
• Internet Explorer: Supported since version 9.0.
• Opera: Supported since version 10.5.
• Safari: Supported since version 5.0.

See Also

For more information and related properties, you may find the following resources helpful:

• border-radius: The shorthand property that sets the radius for all four corners of an element.
• border-top-right-radius: Specifies the radius of the top-right corner of an element.
• border-bottom-right-radius: Specifies the radius of the bottom-right corner of an element.
• border-bottom-left-radius: Specifies the radius of the bottom-left corner of an element.

Additional Resources

• CSS Backgrounds and Borders Module Level 3: Official specification for border-radius properties.
• MDN Web Docs: Detailed documentation and examples for border-top-left-radius.
• W3C CSS Validation Service: A tool to validate your CSS code.

Learning Resources

• CSS Tricks: Comprehensive guide to using border-radius.
• CSS-in-Depth: In-depth article on advanced border radius techniques.

FAQs

What does the border-top-left-radius property do?

It rounds the top-left corner of an element. You can control the curvature using specific values like pixels or percentages.

How do I create a fully rounded top-left corner?

Set the radius to 50%. For example: border-top-left-radius: 50%;.

Can I use different horizontal and vertical radii?

Yes, you can define different radii by specifying two values. For example: border-top-left-radius: 20px 40px;.

How does border-top-left-radius work with overflow properties?

It affects how content overflows in the top-left corner. With overflow set to hidden, the curved corner will mask content, creating a rounded clipping effect.

Can I animate border-top-left-radius?

Yes, the border-top-left-radius property can be animated.

Is border-top-left-radius supported in all browsers?

It is widely supported in all modern browsers, including Chrome, Firefox, Safari, Edge, and Opera. It is also supported in Internet Explorer from version 9 onwards.

What happens if I use the border-radius shorthand property?

If you set the border-top-left-radius value using the border-radius shorthand property, the border-top-left-radius value will be reset to its initial value.

How do I apply border-top-left-radius to a specific element?

You can apply it to any HTML element by including it in your CSS. For example:

.my-element {
  border-top-left-radius: 15px;
}

Can I use percentage values with border-top-left-radius?

Yes, you can use percentage values. The percentage refers to the corresponding dimension of the border box. For example:

.my-element {
  border-top-left-radius: 50%;
}

How does border-top-left-radius interact with other border properties?

It works in conjunction with other border properties to create visually appealing designs. You can combine it with properties like border-style, border-width, and border-color to customize the appearance of the element’s border.

What if I need to support older browsers that don’t support border-top-left-radius?

Consider using fallbacks or polyfills to ensure a consistent user experience. Alternatively, use progressive enhancement to provide a basic experience for older browsers while offering enhanced features for modern browsers.