Carousel-of-post-images style sheet issue

I have installed the “Carousel-of-post-images” plugin on to my word press site and when I activate it, it has overridden my theme style sheet. I have gone in to the settings and changed the skin to use as tango. I have made changes to that style sheet to suit. But I can’t work out why it has changed our fonts, tables, menus etc in the rest of our site. We are using the Simplistic Blue 1.3.2 by Carsen Klock
theme.

https://www.ads-software.com/extend/plugins/carousel-of-post-images/