App thumbnail background stripes in header

[henrikalmen]

We recently upgraded to QSEoW version May 2025 (from May 2024) and some of the layout has changed. 

What's up with the behaviour of the thumbnail displayed on top of the app? It's a square! And if the thumbnail is not a square (and i'ts not supposed to be!), gray stripes are added on the top and at the bottom:

This is caused by this line in qlik's main css: .css-x1voqc {background:#0000000D}

It's possible to override that in a custom theme css, with the exception of the app overview when an app is first opened, since the theme is not loaded there. 

This raises questions. Why has the qlik dev team decided to make that thumbnail placement a square (32x32 pixels), when the documentation suggests the proportions 8:5 for thumbnails? (Although those proportions don't seem correct, as I have written about here: Sheet thumbnail dimensions.) And why was it considered a good idea to add gray banners around a correctly sized app thumbnail?

It also raises the question why I can't find other discussions on this topic in the community - I can't be the only one being disturbed by this? But maybe I just didn't search the forum enough. Or I'm just very sensitive...