Created attachment 172824 [details]
Screenshot showing the problem.

I have Okular installed in Ubuntu 24.04 installed via snap. It runs well, but the main window and any child windows are drawn without drop shadows or borders. It makes it difficult to differentiate where one window end and other start.  See attached screenshots.

Snap info:

❯ snap info okular
name:      okular
summary:   Document Viewer
publisher: KDE✓
store-url: https://snapcraft.io/okular
contact:   https://bugs.kde.org/enter_bug.cgi?product=neon&component=Snaps
license:   GPL-2.0+ AND GFDL-1.3
description: |
  Okular is a universal document viewer developed by KDE. Okular works on multiple platforms,
  including but not limited to Linux, Windows, Mac OS X, \*BSD, etc.
  
  Features:
  
  - Supported Formats: PDF, PS, Tiff, CHM, DjVu, Images, DVI, XPS, ODT, Fiction Book, Comic Book,
  Plucker, EPub, Fax
  - Sidebar with contents, thumbnails, reviews and bookmarks
  - Annotations support
commands:
  - okular
snap-id:      SfUqQ280Y4bJ0k64qtBKTTXq5ml46tvQ
tracking:     latest/stable
refresh-date: hoy a las 09:52 -03
channels:
  latest/stable:    24.05.2 2024-08-04 (156)  68MB -
  latest/candidate: 23.08.5 2024-04-12 (152) 277MB -
  latest/beta:      ↑                              
  latest/edge:      24.05.2 2024-08-02 (156)  68MB -
installed:          24.05.2            (156)  68MB -