Box Sizing

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

Include borders and padding

Use boxSizing="border-box" 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.

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

<x.div boxSizing="border-box" h={32} w={32} p={4} border={4}>
  {/* ... */}
</x.div>

Exclude borders and padding

Use boxSizing="content-box" 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.

<x.div boxSizing="content-box" h={32} w={32} p={4} border={4}>
  {/* ... */}
</x.div>

Responsive

To control the box-sizing at a specific breakpoint, use responsive object notation. For example, adding the property boxSizing={{ md: "content-box" }} to an element would apply the boxSizing="content-box" utility at medium screen sizes and above.

<x.div boxSizing={{ md: 'content-box' }} />

For more information about xstyled's responsive design features, check out Responsive Design documentation.