It appears that the css you shared is not in a media query when quickly looking through the html from your site, however the browser inspector tool shows that it's in a media query (2x):
@media screen and (min-width: 768px)
@media screen and (min-width: 768px)
.page-id-16713 .cta-2-banner-2 {
display: none;
}
This means there might be invalid css somewhere before this property that is causing trouble. Browsers try to make sense of these things and that's why it's in a media query. I recommend a w3c validator or taking all your css into your code editor and combing through it.
The quickest fix (although not the recommended cause the real invalid issue should be resolved to prevent future trouble):
@media only screen and (max-width: 40em) {
.page-id-16713 .cta-2-banner-2,
.page-id-16713 .quotes-wrapper {
display: none
}
}