Syntax highlighting in ipynb files only works for default "White" theme
Summary
Syntax highlighting in ipynb (IPython notebooks) files only works for default "White" syntax highlighting theme, selectable under "Settings - Preferences" . If another theme is selected, which works fine for inline code, e.g. in Issues, there is no syntax highlighting when viewing the ipynb files.
If I remember correctly the syntax highlighting for ipynb was always in the style "White" in older versions of gitlab, independent of what was selected in the preferences. But these versions had a problem with correctly rendering the rich notebook output. Maybe this issue is related to the work in https://gitlab.com/gitlab-org/gitlab-ee/issues/18258 and already merged fixes.
Steps to reproduce
Look at this notebook and change between "White" (default) syntax highlighting and something else, e.g. "Monokai". You will see that syntax highlighting only works with "White".
What is the current bug behavior?
Syntax highlighting in ipynb (IPython notebooks) files only works for default "White" syntax highlighting theme
What is the expected correct behavior?
Syntax highlighting in ipynb (IPython notebooks) files works for all syntax highlighting themes, which implies that also background color change.
Maybe it would be better to have a separate option in the preferences to choose a color theme for ipynb files.
Relevant logs and/or screenshots
Example IPython notebook with non-working syntax highlighting after choosing "Monokai"
Same notebook as above, but with correctly working "White" syntax highlighting:
Output of checks
This bug happens on GitLab.com (and also on our local GitLab Enterprise Edition 12.2.5-ee)