Change color of category list in widget to link blue?

Hi
I am very new to WordPress and just upgraded to Pro version of iconic one to try and get more control over my site’s appearance.
Offgridhomesteadprepper.com
I am trying to change the color of the text of the Categories list from my widget on the sidebar. I want the text to be blue so people know if is linkable/clickable. This was the default in my last theme so I liked the way it looked.
On the forum here I found this code go put in custom CSS
a {
color: #0000FF;
}
I added that but nothing happened. I suspect that code will only affect the links in the body of my posts and pages (which is cool since that will save me time on future posts if it works).
I looked thru the php files but where as there are a few widget files, I didn’t see one for categories just the one huge category php where I am guessing this control might be buried.
I am sure hoping I don’t have to mess with any php files because I will have to figure out how to do a child theme then correct?
Thanks for any assistance and please dumb it down for a newbie like me.
Cheryl