Icon backgrounds

[SoPat712]

These icons look invisible in white mode, maybe a background for them needs to be added? They look fine in dark mode however, but black icons become kind of hard to read then, obviously.

[chkpwd]

We may need to add a check for the hex to determine an appropiate background for it. I'll be on vacation tomorrow, I'll try my best to release a fix tonight.

[chkpwd]

In tangent with issue #18, it's best we rework the way Simplepycons is being used within the project. For now, this issue will remain stale until we make progress on the aforementioned issue.