Need help using in Divi

I’m using Divi to build my ww.wp.xz.cn site. I have the WPshowhide plugin installed and would like to customize the font size, type, and color that shows up when it says “Show more…”. But I can’t figure out how to do it and need help.

Here’s the CSS code I’m using: span#post-toggle-50 { font-family: ‘Montserrat’; font-size: 18px; font-weight: bold; color: #66BC1B ; }

I know nothing about CSS. Apparently, I’m doing something wrong because the font isn’t changing to meet the specifications I want. Help please!