Profile banners are cut off about 25% of their height in the Merveilles default theme.

[LiminalCrab]

Steps to reproduce the problem

1. Go to Settings -> Preferences -> Site Theme
2. Select the Merveilles theme
3. Go back to your profile and view the banner.
   .

Expected behaviour

It should show the full 580x125 banner image.

Actual behaviour

About 25% of the banner image is cut off.

Detailed description

For the account_header_image class, the img tag within it is cut off about 25% of its height resulting in this behavior:

The other themes present it with the proper behavior, here's an example with the Mastodon dark theme:

![Screenshot_20240406_121304](https://github.com/merveilles/merveilles-town/assets/78995156/67ec9e7e-8ddc-4a9f-9315-fa69923693e3

Specifications

v4.0.15+hometown-1.1.1

Tested in both Firefox, Chrome, and the Toot application for iphone.