Plugin causes display problems on theme

The file css/normalize.min.css causes problems with layout of the wordpress search widget in my theme. I was able to fix this by modifying the CSS file to comment out the specifications that caused the problem — but I thought you should be aware that the file can cause theme conflicts. This is on a popular theme (Mantra) which has reported active installations of 20,000+

But perhaps including normalize.css with a plugin is not such a good idea, given the possibility of overriding theme settings?