https://www.moscatotartufi.it/approfondimenti/
.av-masonry-entry-title.entry-title h3 {font-size:18px!important;}
do not work
try this:
.av-masonry-entry.av-masonry-entry-title {font-size: 18px !important}
the h3 is before (cascading style sheet) these classes – means:
h3.av-masonry-entry.av-masonry-entry-title {font-size: 18px !important}
but the code above should work too!
And because of the two classes are on the same element there must be no space between them!
by the way: the rule comes from shortcodes.css line 2511 and there is a space between the two classes – which is on my opinion wrong.