Edit Web App Styles CSS

[new11]

Hello, I hope everyone's going well!
I've just discovered this great website and am still exploring everything so my apologies if this is placed in the incorrect space.

Quick question; does anyone know how to permanently edit the styles for the Synology web apps?
What I'm hoping to achieve is to change the background for synology photos from white to black across the board. I know I can use "dark reader" extension. However, when sharing photos/albums to clients, family and friends, this is something they obviously wouldn't be doing. The white spaces really fatigue the eyes, something that I dont want other poeple to experience when sharing precious photos.

I've added a few screen shots of the look I'm hoping to go for.
Many thanks in advance for any ideas!

 

[Rusty]

All changes to the Photos app can be done using .../webman/3rdparty/SynologyPhotos/style.css file. Be sure to backup!

 

[WST16]

change the background for synology photos from white to black across the board

If all fails and you must have black, take a look at Lychee.

 

[new11]

All changes to the Photos app can be done using .../webman/3rdparty/SynologyPhotos/style.css file. Be sure to backup!

Thanks for that, its one more step in the right direction! I was looking over the "style.css" file and am a little lost ahha. You wouldn't happen to know what tag/selector I should be editing, by any chance do you? or even what I should be looking for, my coding skills are quite basic. ahah
Cheers

-- post merged: 14. Dec 2021 --

If all fails and you must have black, take a look at Lychee.

I would have never even known about that, Thank you! It's definitely something to look at in future.

 

[Rusty]

You wouldn't happen to know what tag/selector I should be editing, by any chance do you?

Using browser web editor, you should easily pinpoint the css element needed for this, but no, I don't know it by heart