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box-sizing

main Ver versión oficial en línea Licencia MITDescargado el 2026-09-15 Bundle .md (1.3 MB) ↓

En esta página
Clase Propiedades CSS
box-border box-sizing: border-box;
box-content box-sizing: content-box;

Examples#

Including borders and padding#

Use the box-border utility 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:

{

{/ w-measure indicator /}
{/ Horizontal line /}
{/ Left chip /}
{/ Badge /}
128px
{/ Right chip /}
{/ h-measure indicator /}
{/ Vertical line /}
{/ Top chip /}
{/ Badge /}
128px
{/ Bottom chip /} 

      </div>
    </div>
  </div>
  <div className="col-start-3 row-start-2 bg-white dark:bg-gray-900"></div>
  <div className="col-start-1 row-start-3 bg-white dark:bg-gray-900"></div>
  <div className="col-start-2 row-start-3 bg-white dark:bg-gray-900"></div>
  <div className="col-start-3 row-start-3 bg-white dark:bg-gray-900"></div>
</div>

}

<!-- [!code classes:box-border] -->
<div class="box-border size-32 border-4 p-4 ...">
  <!-- ... -->
</div>

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

Excluding borders and padding#

Use the box-content utility 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:

{

{/ w-measure indicator /}
{/ Horizontal line /}
{/ Left chip /}
{/ Badge /}
128px
{/ Right chip /}
{/ h-measure indicator /}
{/ Vertical line /}
{/ Top chip /}
{/ Badge /}
128px
{/ Bottom chip /} 

      </div>
    </div>
  </div>
  <div className="col-start-3 row-start-2 bg-white dark:bg-gray-900"></div>
  <div className="col-start-1 row-start-3 bg-white dark:bg-gray-900"></div>
  <div className="col-start-2 row-start-3 bg-white dark:bg-gray-900"></div>
  <div className="col-start-3 row-start-3 bg-white dark:bg-gray-900"></div>
</div>

}

<!-- [!code classes:box-content] -->
<div class="box-content size-32 border-4 p-4 ...">
  <!-- ... -->
</div>

Responsive design#