Think of a way to improve partner logo's in dark mode

One-sentence description

Think of a way to improve partner logo's in dark mode

Motivation

With current dark mode, some partner logo's look a bit weird

Desired functionality

They should look good both in dark mode and light mode. Both in the banner, and in the vacancy pages

Suggested implementation

It is hard to do this correctly for all logo's. One way is to add a css filter in dark mode that makes the logo's more white. Another way could be to just support a dark mode and light mode logo.