Plugin makes unwanted CSS changes

I’m using an Event Registration Plugin (https://wpeventregister.com.

When I added an event, it made the text fields height 1/2 the size and you can only read the lower half of the input.

I’ve tried to overwrite the style using my style.css file in the child-theme, but I suspect this is not correct.

I imagine I don’t want to edit the plugins css file directly.

Here is a link to the page in question: https://www.stingtravelbaseball.org/upcoming-events/2014-sting-shootout/

Any insight would be really appreciated.