Dark theme doesn't seem to affect Vivaldi

[WetGeek]

Summary

This is the theme that I'm using. I think it's the default, because I don't remember choosing it, but it's what I would have chosen regardless. My eyes are rather ensitive to bright light.

The theme apparently applies to the applications that are part of the Xfce DE, but not to one that I installed from the repository--in particular, Vivaldi. Opening any of the many sites that it hosts provides a painful blast of white light.

Steps to reproduce

Just launch Vivaldi (on hardware) and you should notice right away that it is not using any kind of dark theme.

Expected result

I expected web pages to be displayed in a dark theme, as they are on a fully-updated Xfce RC2 VM that runs on my daily-driver laptop. (See similar image in comment below.)

Actual result

This should be dark as well (Xfce on bare metal) but it's apparently unaffected by the theme. I have no idea why the hardware version differs from the virtual version, but as I pointed out, it's painful to look at.

Environment

• [X] Is system up to date?

Repo

Shannon (stable)

Desktop Environment

Xfce

System details

Other comments

No response

[WetGeek]

In comparison, this is a screenshot of the same full-screen image, taken from Vivaldi running on an Xfce VM that's fully updated, the same as the image above.

[TraceyC77]

I was able to reproduce this on a fresh XFCE 4.5 RC5 installation on a VMM VM. There was no customization. The problem is confirmed and is specific to XFCE.

Reproduction Steps:

1. Booted into the XFCE VM after installation. The theme that was set by default was the same one in the report (Qogir-Dark).
2. Checked for updates, none were available.
3. Vivaldi is not installed by default, installed vivaldi-stable through Software Center.
4. Launched Vivaldi. Went through the setup including "Choose your style". Note: The default style "Vivaldi" is white with a red bar on top. The "Dark" style matches the screenshots, having a dark bar and tabs, so I chose that.
5. Opened this issue in Vivaldi on the VM.

Result

Confirmed that Vivaldi displays a white background on pages. In contrast, Firefox displays a dark background. This was true for other pages as well, such as duckduckgo.com.

Results in Other DEs

In contrast, both Firefox and Vivaldi display these pages with a dark background / theme as expected for me on Plasma unstable. Tested on a fresh Budgie VM with 4.5 RC5, also using the default theme (which is dark), it displays pages correctly with a dark background.

[EbonJaeger]

I've discovered that switching to another theme and then back to Qogir-Dark makes Vivaldi correctly use dark mode on websites. This leads me to believe that there is a setting somewhere that we're not setting by default, but should be. I asked in the XFCE Matrix channel about what it might be, but they haven't gotten back to me yet.