Are template CSS files overriding my addon style sheets?

Are template CSS files overriding my addon style sheets?

Trying to achieve styling for a table. Using the code below. However the the output seems to conflict with the template, mega nav won't roll down to subs, something is pushing other elements askew.

I believe it is the CSS file alone, albiet there is an accompanying javascript file. Using these external files.

Usage:

<table id="mytable"

Thank you for your time.

I'll replicate the site to a non production server and get the url to it soon.