CSS Border-Image Enhance Design with Custom Borders

Formal Definition

The border-image property in CSS is a powerful tool that lets you use custom images as borders around elements. Understanding its formal definition helps you see how this property works and how it interacts with other CSS properties.

Initial Values

The initial values for the border-image property are:

• border-image-source: none
• border-image-slice: 100%
• border-image-width: 1
• border-image-outset: 0
• border-image-repeat: stretch

Applies To

The border-image property applies to all elements that can have a border, such as div, p, button, and more.

Syntax

The basic syntax for the border-image property is:

border-image: source slice width outset repeat | initial | inherit;

Values

1. source

   • Specifies the image or gradient used as the border.
   • Example: url('border.png'), linear-gradient(red, blue)

2. slice

   • Defines how the source image is sliced into regions.
   • Example: 27, 30%

3. width

   • Sets the width of the border image.
   • Example: 35px, 1rem

4. outset

   • Specifies the distance by which the border image is extended beyond the element’s border box.
   • Example: 1rem, 10px

5. repeat

   • Determines how the border image is repeated or stretched.
   • Example: stretch, repeat, round, space

Example Usage

Here’s how you can use the border-image property in your CSS:

/* Basic usage */
border-image: url('border.png') 30 round;

/* With width and outset */
border-image: url('border.png') 30 / 20px / 10px round;

/* Using a gradient */
border-image: linear-gradient(red, blue) 30 round;

Accessibility

While border-image can make your web elements look great, it’s important to consider accessibility. Not all users can see images, so make sure the border image doesn’t contain essential information. If it does, provide a text alternative.

Summary

The border-image property is a versatile tool for creating visually appealing borders. By understanding its syntax and values, you can customize borders to fit your design needs. Just remember to keep accessibility in mind to ensure a good experience for all users.

For more details, check out the full compatibility table and provide any feedback here.

Border Image Property

The border-image property in CSS lets you use images as borders for elements, except for internal table elements when border-collapse is set to collapse. It also works with the ::first-letter pseudo-element.

Key Points

• Inherited: border-image is not inherited from parent elements.
• Percentages: Used in border-image-slice (size of the border image) and border-image-width (width or height of the border image area).
• Computed Value:
  • border-image-outset: As specified, with relative lengths converted to absolute lengths.
  • border-image-repeat: As specified.
  • border-image-slice: One to four percentages or absolute lengths, plus the keyword fill if specified.
  • border-image-source: none or the image with its URI made absolute.
  • border-image-width: As specified, with relative lengths converted to absolute lengths.
• Animation Type:
  • border-image-outset: By computed value type.
  • border-image-repeat: Discrete.
  • border-image-slice: By computed value type.
  • border-image-source: Discrete.
  • border-image-width: By computed value type.

Formal Syntax

border-image =
  [<'border-image-source'>] ||
  [<'border-image-slice'> || / [<'border-image-width'>] || / [<'border-image-outset'>] ||
  [<'border-image-repeat'>];

<border-image-source> =
  none | <image>;

<border-image-slice> =
  [ [<number> | <percentage>] {1,4} ] && fill?;

<border-image-width> =
  [ [<length-percentage> | <number> | auto] {1,4} ];

<border-image-outset> =
  [ [<length> | <number>] {1,4} ];

<border-image-repeat> =
  [ [stretch | repeat | round | space] {1,2} ];

<image> =
  <url> | <gradient>;

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

<url> =
  url(<string> <url-modifier>*) | <src()>;

<src()> =
  src(<string> <url-modifier>*);

Examples

Bitmap

HTML:

<div id="bitmap">
  This element is surrounded by a bitmap-based border image!
</div>

CSS:

#bitmap {
  width: 200px;
  background-color: #ffa;
  border: 36px solid orange;
  margin: 30px;
  padding: 10px;
  border-image: url("border.png") 27 / 36px 28px 18px 8px / 18px 14px 9px 4px round;
}

Explanation:

• border-image uses border.png as the source.
• 27 slices the image.
• 36px 28px 18px 8px sets the border width.
• 18px 14px 9px 4px sets the outset.
• round ensures the border slices fit evenly.

Gradient

HTML:

<div id="gradient">
  This element is surrounded by a gradient-based border image!
</div>

CSS:

#gradient {
  width: 200px;
  border: 30px solid;
  border-image: repeating-linear-gradient(45deg, #f33, #3bf, #f33 30px) 60;
  padding: 20px;
}

Explanation:

• border is 30px solid.
• border-image uses a repeating linear gradient.
• 60 slices the gradient image.
• padding is 20px.

Rounded Borders

HTML:

<div id="rounded">
  This element is surrounded by a border image with rounded corners!
</div>

CSS:

#rounded {
  width: 200px;
  border: 10px solid transparent;
  padding: 20px;
  border-radius: 20px;
  background-image: linear-gradient(white, white), linear-gradient(to right, cyan, lime);
  background-origin: border-box;
  background-clip: padding-box, border-box;
}

Explanation:

• border is 10px solid transparent.
• background-image creates a gradient background.
• background-clip ensures the background is clipped to the padding box and border box.

Summary

The border-image property lets you create visually appealing borders using images or gradients. By understanding the syntax and examples, you can enhance your web designs with unique and engaging border styles.

Specifications

The border-image property is defined in the CSS Backgrounds and Borders Module Level 3. Understanding this helps ensure compatibility across browsers.

Key Highlights

• Properties: border-image-source, border-image-slice, border-image-width, border-image-outset, border-image-repeat.
• Syntax: Ensures correct usage.
• Behavior: Describes slicing, repeating, and positioning.

Importance

Following specifications ensures consistency and compatibility across browsers.

Summary

The border-image property’s specifications help create consistent and compatible designs. For details, refer to the CSS Backgrounds and Borders Module Level 3.

Browser Compatibility

The border-image property is widely supported. Here’s a compatibility table:

Best Practices

• Fallback Styles: Provide fallbacks for older browsers.
• Prefixes: Use vendor prefixes if needed.
• Testing: Regularly test across different browsers and devices.

Summary

Understanding browser compatibility ensures your designs work consistently. Always test and provide fallbacks for the best user experience.

For the latest information, refer to the Browser Compatibility Data.

See Also

For further reading and related properties:

• border
• outline
• box-shadow
• background-image
• <url> type
• Gradient functions:
  • conic-gradient()
  • repeating-conic-gradient()
  • linear-gradient()
  • repeating-linear-gradient()
  • radial-gradient()
  • repeating-radial-gradient()

Additional Resources

• Border images in CSS: A key focus area for Interop 2023 on MDN blog (2023)

Summary

These resources provide additional context for CSS borders and images. Explore them to deepen your understanding and enhance your design skills.

Help Improve MDN

MDN Web Docs is a collaborative project that relies on contributions from the community. Your feedback and contributions are invaluable in improving the quality and accuracy of the documentation.

How to Contribute

• Learn how to contribute: Visit the MDN Contribution Guide to learn how you can contribute to the project.
• Report issues: If you find any issues or have suggestions for improvement, you can report them on the MDN GitHub repository.

Get Involved

Your involvement in improving MDN helps ensure that the documentation remains up-to-date, accurate, and useful for the web development community. Whether you’re reporting a typo, suggesting a new example, or contributing a detailed explanation, your efforts make a significant difference.

Thank you for your support and contributions!

View this Page on GitHub

You can view the source code for this page on GitHub by visiting the GitHub repository for this page. This allows you to see the raw content, make suggestions, or contribute to the documentation directly.

By exploring the GitHub repository, you can gain insights into how the documentation is structured and contribute to its improvement. Whether you are fixing a typo, adding an example, or providing a detailed explanation, your efforts help ensure that the documentation remains accurate and useful for the web development community.

How to Contribute

1. View the Source Code: Navigate to the GitHub page to see the raw content of this page.
2. Suggest Changes: If you spot any issues or have suggestions for improvement, you can propose changes directly on GitHub.
3. Contribute: Follow the MDN Contribution Guide to learn how to contribute to the project.

Get Involved

Your involvement in improving MDN helps ensure that the documentation remains up-to-date, accurate, and useful for the web development community. Whether you’re reporting a typo, suggesting a new example, or contributing a detailed explanation, your efforts make a significant difference.

Thank you for your support and contributions!

Report a Problem with this Content

If you encounter any issues with the content on this page, such as errors, omissions, or outdated information, we encourage you to report them. Your feedback helps us improve the quality and accuracy of the documentation.

How to Report a Problem

1. Visit the GitHub Repository:

   • You can report a problem directly on the GitHub repository for this page.

2. Provide Details:

   • Include a description of the issue.
   • Specify where the issue is located.
   • Suggest improvements if possible.

3. Submit the Issue:

   • Fill out the form and submit it. Our team will review your report.

Why Your Feedback Matters

Your feedback is crucial for maintaining high-quality documentation. By reporting issues, you help ensure that the information is accurate and useful for the web development community.

Thank You

We appreciate your support and contributions. Your efforts make a significant difference in improving the documentation and helping others in the community.

Thank you for your support and contributions!

Supported Browsers

The border-image property in CSS is widely supported across many modern browsers, ensuring that your designs look consistent and appealing. Below is a list of browsers and their versions that support the border-image property:

• Google Chrome: Supported since version 16.0, released in December 2011.
• Firefox: Supported since version 15.0, released in August 2012.
• Internet Explorer: Supported since version 11.0, released in October 2013.
• Opera: Supported since version 15.0, released in May 2013.
• Safari: Supported since version 6.0, released in July 2012.

Summary

The border-image property is well-supported across major browsers, making it a reliable choice for enhancing the visual appeal of your web designs.

FAQs

What is the border-image property in CSS?

The border-image property allows you to use an image as a border instead of a solid color. It provides control over how the image is sliced, resized, and applied around the element.

How do I use the border-image property to create a custom border?

To use the border-image property, follow these steps:

1. Specify the Image Source:

   border-image-source: url('border.png');

2. Define the Slice Values:

   border-image-slice: 27;

3. Set the Width:

   border-image-width: 35px;

4. Specify the Outset:

   border-image-outset: 1rem;

5. Control the Repeat Behavior:

   border-image-repeat: round;

Combining these properties:

border-image: url('border.png') 27 / 35px / 1rem round;

Can I apply border-image to only one side of an element?

The border-image property applies to all sides of an element. For a custom border on just one side, use alternative approaches like background images or pseudo-elements.

What is the difference between border-image and border?

The border property sets the style, width, and color of an element’s border, typically using solid colors or predefined styles. The border-image property allows you to use an image or gradient as the border, providing more design flexibility.

Why isn’t my border-image displaying correctly?

If your border-image is not displaying correctly, consider the following:

1. Check the Image Path: Ensure the image path is correct.
2. Specify border-style: Set border-style to something other than none.

   border-style: solid;

3. Adjust Slice and Width Values: Ensure border-image-slice and border-image-width values are correctly set.
4. Use Fallback Styles: Provide fallback styles for browsers that do not support the border-image property.

How do I ensure accessibility with border-image?

To ensure accessibility when using the border-image property:

1. Text Alternatives: Provide a text alternative if the border image contains critical information.
2. Contrast: Ensure the border image does not compromise the readability of the text or other important content.
3. Screen Readers: Screen readers cannot parse border images. If the image conveys meaningful information, include that information in the text or use ARIA attributes.

Summary

The border-image property in CSS is a powerful tool for creating visually appealing and customized borders. By understanding how to use the property and following best practices for accessibility, you can enhance the design of your web pages and ensure that they are accessible to all users.