Adaptive Width

In some cases, we need to make the floating element and the reference element above it have the same width, which can be achieved using CSS or JS.

Adaptive width using CSS

To achieve adaptive width using CSS, we can add the following settings:

First add as="div" and className="relative" to the <Float> component, render the periphery as <div className="relative">, and then add floatingAs={Fragment} let no elements be rendered around the floating element (the default will render a layer of <div> elements), directly position the floating element, and finally add the w-full class to the reference element and the floating element and you are done.

Now the button and options will have the same width:

import { Fragment } from 'react'

<Listbox>
  <Float
    as="div"
    className="relative"
    placement="bottom"
    offset={4}
    floatingAs={Fragment}
  >
    <Listbox.Button className="w-full ...">
      ...
    </Listbox.Button>

    <Listbox.Options className="w-full ...">
      ...
    </Listbox.Options>
  </Float>
</Listbox>

Of course, you can also specify the width directly:

<Listbox>
  <Float
    ...
    className="relative w-[260px]"
    ...
  >
    ...
  </Float>
</Listbox>

If you put it in a flex container to fill the width, you need to add the w-full class:

<div className="flex justify-center items-center">
  <Listbox>
    <Float
      ...
      className="relative w-full"
      ...
    >
      ...
    </Float>
  </Listbox>
</div>

Adaptive width using JS v0.10+

There are cases where CSS relative does not properly synchronize the width of the floating element, such as when using the portal at the same time. At this point, you can use the adaptiveWidth prop, which uses the ResizeObserver API to monitor the width of the reference element and synchronize it to the floating element, but the performance will be worse than the CSS implementation.

<Float adaptiveWidth>