themes

Hello! I wanted to change the subject, which I did later,but not in the way I intended. As a result, the question remains, wh ... s error? Why exactly with AppCompat interaction should I use themes? Why can't they just be put in the standard way? Thanks.

There is a website with themes for bootstrap bootswatch.com, there you can download themes as a bootstrap.min.css file. Q: How do I enable this theme? Just replace the regular bootstrap. min. css with this file?

Where can I download ready-made color schemes for VS 17 ? Maybe there are ready-made solutions for the ColorThemes plugin somewhere ?