Custom Theme Variants Repeat Background

[TheCuteFoxxy]

Describe the bug
Custom variants of the shipped themes, cause a repeated background, despite using identical image assets. This has been specifically observed on the "Blurred" theme and and themes using non-shipped assets.

To Reproduce
Steps to reproduce the behavior:

1. Copy an existing theme
2. Modify the styles.css to match LoveDark CSS
3. Clear caches
4. Select new theme
5. Observe tiling

Expected behavior
The theme should cover the full viewport without repeating.

Screenshots
Correctly Displayed "LoveDark" theme

Incorrectly Displayed "Blurred" theme with custom css and shipped assets

Incorrectly Displayed Custom theme with custom css and non-shipped assets

Please complete the following information:

• Browser: Firefox 109.0 (64-bit)
• PHP version: 7.4
• SnappyMail Version: 2.25.4

Additional context
The CSS used in my dark variation of "Love" is identical to the CSS being used in the new theme variants.

[the-djmaze]

Correct. background-size: cover; will solve that.

[TheCuteFoxxy]

Correct. background-size: cover; will solve that.

We thought so to, but it did not do so for us. Are you able to reproduce an instance of this working using the CSS?

[TheCuteFoxxy]

We are using the following CSS for MAIN

	--main-color: #fff;
	--main-bg-color: #48525C;
	--main-bg-image: url("images/background.jpg");
	--main-bg-size: cover;