pdfjs buttons unreadable with darkmode enabled

[hseg]

Version info:

qutebrowser v2.3.0
Git commit: 
Backend: QtWebEngine 5.15.5, based on Chromium 87.0.4280.144
Qt: 5.15.2

CPython: 3.9.5
PyQt: 5.15.4

sip: 6.1.0.dev2104271705
colorama: 0.4.4
jinja2: 3.0.1
pygments: 2.9.0
yaml: 5.4.1
adblock: 0.5.0
PyQt5.QtWebEngineWidgets: yes
PyQt5.QtWebEngine: 5.15.4
PyQt5.QtWebKitWidgets: yes
pdf.js: 2.9.359 (/usr/share/pdf.js/build/pdf.js)
sqlite: 3.36.0
QtNetwork SSL: OpenSSL 1.1.1k  25 Mar 2021

Does the bug happen if you start with --temp-basedir?: Only if invoked as qutebrowser --temp-basedir --set colors.webpage.darkmode.enabled true

Description With darkmode enabled, pdf.js's buttons render as black on dark gray, which is hard to read.

How to reproduce

• qutebrowser --temp-basedir --set colors.webpage.darkmode.enabled true
• Open any PDF in pdf.js

[The-Compiler]

Screenshot:

This is mostly an issue between PDF.js and Chromium's dark mode, but I guess qutebrowser could inject some CSS to work around it.

[tinywrkb]

@The-Compiler this seems safe to close, I don't see a problem with a recent pdf.js version.
BTW, there's now an interesting forcePageColors setting.