[ Feature request ] apply dark mode on tab loading

[MR-Diamond]

Tab Session Manager version 7.0.1
Firefox version 134.0.2

I've set everythinbg to dark colours, so also in Tab Session Manager (dark theme), however, when restoring tabs with Tab Session Manager, while the tabs are restoring, the background is white: this doesn't occurs when I restore the tabs with the built-in option of Firefox "Restore Previous Session".

[MR-Diamond]

when restoring tabs with Tab Session Manager, while the tabs are restoring, the background is white

I installed the addon Dark Background Preload and also tweaked UserChrome.css and UserContent.css; now, on loading, the background is dark.