When using KDE Breeze Dark as the system theme, the graph view on the caller / callee tab is unreadable

Describe the bug

The boxes and especially the arrows are barely visible in the graph view. They should use a colour relative the background colour.

To Reproduce Steps to reproduce the behavior:

1. Use a dark theme, such as Breeze Dark in KDE Plasma
2. Open a perf recording
3. Click on a function with callers/callees in the caller/callee view.
4. Squint trying to make things out.

Expected behavior Reasonably contrasting colours for both light and dark themes.

Screenshots

Version Info (please complete the following information):

• Linux Kernel version: 6.16.5-zen1-1-zen
• perf version: 6.16-1
• hotspot version (appimage? selfcompiled?): From AUR package on Arch Linux. Claims to be 1.5.80 in about.
• if self-compiled hotspot, what version of elfutils: 0.193-5

Additional context The official AppImage doesn't show this view, which is very odd, since it is supposedly built from the same version? Maybe some missing optional dependency in the official AppImage? There aren't any patches in the AUR build (except for a small Qt 6.9 build fix which is unrelated).