Box Sizing

Utilities for controlling how the browser should calculate an element’s total size.

Default class reference

Include borders and padding

Use box-border to set an element’s box-sizing to border-box, telling the browser to include the element’s borders and padding when you give it a height or width.

This means a 100px × 100px element with a 2px border and 4px of padding on all sides will be rendered as 100px × 100px, with an internal content area of 88px × 88px.

Tailwind makes this the default for all elements in our preflight base styles.

1. <div class="box-border h-32 w-32 p-4 border-4 ...">
2. <!-- ... -->
3. </div>

Exclude borders and padding

Use box-content to set an element’s box-sizing to content-box, telling the browser to add borders and padding on top of the element’s specified width or height.

This means a 100px × 100px element with a 2px border and 4px of padding on all sides will actually be rendered as 112px × 112px, with an internal content area of 100px × 100px.

1. <div class="box-content h-32 w-32 p-4 border-4 ...">
2. <!-- ... -->
3. </div>

Responsive

To control the box-sizing at a specific breakpoint, add a {screen}: prefix to any existing box-sizing utility. For example, use md:box-content to apply the box-content utility at only medium screen sizes and above.

1. <div class="box-border md:box-content ...">
2. <!-- ... -->
3. </div>

For more information about Tailwind’s responsive design features, check out the Responsive Design documentation.

Customizing

Variants

By default, only responsive variants are generated for box-sizing utilities.

You can control which variants are generated for the box-sizing utilities by modifying the boxSizing property in the variants section of your tailwind.config.js file.

For example, this config will also generate hover and focus variants:

1. // tailwind.config.js
2. module.exports = {
3. variants: {
4. extend: {
5. // ...
6. +       boxSizing: ['hover', 'focus'],
7. }
8. }
9. }

Disabling

If you don’t plan to use the box-sizing utilities in your project, you can disable them entirely by setting the boxSizing property to false in the corePlugins section of your config file:

1. // tailwind.config.js
2. module.exports = {
3. corePlugins: {
4. // ...
5. +     boxSizing: false,
6. }
7. }

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