Buttons miss styling on the katalogus page in a list view

[stephanie0x00]

Describe the feature
The buttons on the katalogus page when you are in the 'List' view do not have styling. This means that it is visually not clear whether the button is enabled or disabled, as they all look the same.

To Reproduce
Steps to reproduce the behavior:

1. Go to Katalogus.
2. Click on the list view
3. Observe that the buttons miss styling.

Expected behavior
It should be visually clear when a button is enabled or disabled.

Screenshots

OpenKAT version
main