Wrong CSS applying?

I have a WP site in development at https://stalbansilford.org.uk/wordpress/. I’m using a child theme of Discovery. I have a sidebar widget showing recent posts. The CSS which controls this in style.css is set as follows:

#calendar_wrap a {color: #FFF;}

Clearly this doesn’t show up on the white background, so have changed this to
#calendar_wrap a {color: #000;},

in BOTH the original css file AND the child theme css (since the first didn’t work).

In fact neither works, and using Firebug I see that the actual CSS applying is

#calendar_wrap a {color: #FFFFFF;}

I’m at a loss – I can’t find this code anywhere in the site (have searched all the css files I can find and it’s not there.

Can anyone shed light on this?

Cheers.