Update main css from main.min.css changes

Prepare for patch
Apply patch from HPSTR theme (magnific popup)

https://github.com/mmistakes/hpstr-jekyll-theme/commit/980dff4a1a80624e03f97d2eead3df767a0e3a80.patch
Apply git diff from theme: add missed target blank in external links

https://github.com/mmistakes/hpstr-jekyll-theme/commit/774f043104c839760700b0993107bf81fcdd63bd.diff
Magnific popup on links: normal link cursor