Issues with CSS customization

[Coordo1250]

Hello,

I have been trying to customize our OSCP, very simple things such as changing the font type and color, as well as the logo. We use Wordpress to power our website, which was created by a dev company. I am trying to customize it on my own without going through the developer.
I have limited access to the directory and some features which doesn't help, but I managed to get access to it. However, the css code I input in the custom.css file doesn't affect anything. For example, I tried to set the font to red just to see if it is responsive, but no change. Does anyone have an idea as to why?

Thank you!