Inputs have wrong border color with theming

[nickvergessen]

E.g. on the calendar.

Problem is the the border-color is not adjusted:

[nickvergessen]

Similar issue with buttons.
E.g. when you create a new calendar and hover the "Create" button

[skjnldsv]

It will be fixed after we implemented the correct scss variable system for theming (see #2288 )

[nickvergessen]

Also checkboxes are two-colored:

[skjnldsv]

yes, same thing :)