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Last updated: 10 Oct 2022

frontend: Update homepage promotion slots

The three promo boxes on the homepage are used to highlight important information on GOV.UK.

Example image of promotion slots on GOV.UK homepage

To update these promo boxes, you must edit the underlying HTML template for the homepage.

1. Prerequisites

Before updating the promotion slots you must have:

  • the URL of the page that is being promoted
  • an image that is at least 610 x 407 pixels in size in a landscape aspect ratio
  • a title for the promotion (ideally under 25 characters to fit on a single line for most users)
  • some contextual text for the promotion (ideally under 80 characters to spread across two lines for most users)

The image should not contain text as per GOV.UK guidelines. Using text within an image creates accessibility problems. For example, the past homepage promotion slots from March 2020 used text in the images and this approach would now be strongly discouraged.

2. Resize and compress the images

We want the GOV.UK homepage to be optimised towards a fast user experience with a low download size. Central to this is making sure that we serve optimised images. To achieve this, we resize the images and compress the files.

You can use a web tool - Squoosh - to resize and compress the images at the same time. You can use the before and after view to establish the highest level of compression that can be applied before the image quality deteriorates.

Most promo images should ideally be less than 30 kB in size (at time of writing, the current promos are 14 kB, 10.7 kB and 6.3 kB). You might also need to change the format of the image to fit the content - JPGs for a photograph, but maybe PNG for a graphic. It's worth testing to see what gives the smaller file size and the best visual result.

If the image is a photograph, or a detailed graphic, resize the image to all of the following sizes:

  • 610 by 407 pixels
  • 480 by 320 pixels
  • 320 by 213 pixels
  • 240 by 160 pixels
  • 170 by 113 pixels

If the image is a simple graphic, and thus already a small file size, resize it to 610 x 407 pixels.

3. Update the content

The content for the promo slots can be found in the en.yml translation file (no other locales need to be updated). The specific key to look for is promotion_slots. Promo items are stored as a yml list in the order they appear on the homepage. The keys in each list item to update accordingly are:

  • text: the promo description
  • title: the promo title
  • href: the link the promo goes to. This can either be internal (/my-path) or external (
  • image_src: the promo image location. Image should be in the homepage asset directory and can be pulled via homepage/[my-image].png
  • srcset: this is an optional attribute to define promo image srcset values.

You can define srcset values in the yml like so:

  homepage/my-promo.jpg: 610w
  homepage/my-promo-480.jpg: 480w
  homepage/my-promo-320.jpg: 320w
  homepage/my-promo-240.jpg: 240w
  homepage/my-promo-170.jpg: 170w

4. Delete the previous images

You should delete the images that you are replacing from the repository. If we need to use those images again, to perhaps reinstate the promotion later, we can retrieve the images from the Git history.

5. Open a pull request

Finally, you should open a pull request. It is helpful to include information on the source of the change request and to provide a screenshot of the updated promotion slots. You should use the screenshot to confirm with stakeholders that they are happy with the change.