Remove inline styling from QTabPanels

[dsl101]

Is your feature request related to a problem? Please describe.
Using QTabPanels deviates from main app styling unless you remember to reapply background colour to the component.

Describe the solution you'd like
That QTabPanels would just inherit the background colour / style of the containing element and not have inline colour

Describe alternatives you've considered
Trying to remember to reapply styling :)

Additional context
I'm not 100% certain why this component in particular doesn't inherit—perhaps there's a good reason, but if not, it would be much more convenient if it didn't include background: #fff;

[rstoenescu]

Hi,

Sorry but changing the current behaviour would be a breaking change and so definitely not what we want.