Code Interfering with Fonts

Hey there!

I have a client who has custom code in their site that is affecting the fonts (Open Sans) randomly. Sometimes it will work in Chrome windows and sometimes it won't. It never works on mobile view and in Safari browsers. 

I was hoping someone would be able to help me figure out what code is affecting these fonts and to see if they have a solution? 🙂

Url: https://schumacherdesign.ca/

Thanks a ton!

Add to Design > Custom CSS

p {
    font-family: "Open Sans","Proxima Nova","Helvetica",arial,sans-serif !important;
}