Need Help Finding Where to Change Color in css

Working on a client site that I just made live (

Two pages have some content with wrong colors, and I can't seem to find where I can change those colors.

The 'active' tab color is the same as the background and it blends in. I think this is created via the theme's standard 'tabs' shortcode.

The non-active tabs (Feb, Mar, Apr ...) are the same color as the background. These tabs are created using Ultimate Shortcode.

If you need access to the back-end, please let me know and I will set you up with an ID/PW.