Hi there,
Thanks for writing in! Did you add the CSS within page level CSS in Cornerstone settings tab? You can try placing them in Customizer with preceding page ID :
.page-id-3871 div.x-column.x-sm.ourcompany.x-1-2 {
background: rgba(0, 0, 0, 0) linear-gradient(to bottom, rgba(52, 152, 219, 0.9) 0%, rgba(26, 95, 178, 0.6) 100%) repeat scroll 0 0;
}
Add preceding .page-id-3871 for your other CSS as well and move them within Custom > CSS in the Customizer.
Hope this helps.
Cheers!