[BUG] regression background tpos checkout drawer v1.4.0rc2

[CabtonWithaK]

Describe the bug
checkout pane not blurring background

To Reproduce
LNBits 1.4.0rc2
TPOS1.1.4

Additional context
worked well on 1.3.1, probably

[CabtonWithaK]

[talvasconcelos]

Seems a "global" issue with the CSS!