You added this to Additional CSS? Or to style.css? There’s apparently a similar rule that is taking precedence with an !important modifier. It appears to be in Additional CSS. This rule establishes a font size of 25px. I recommend altering this rule instead of adding another.
FYI, Google complains when mobile fonts are smaller than 16px. 16px is generally considered the minimum font size for mobile webpages. Anything smaller can be difficult for some people to read.
The class is called “entry-title”, not “post-title”. Also note that there is another style specification that already forces the size to 25px. So the CSS must look like this:
@media only screen and (max-width: 769px){
h1.entry-title {
font-size:12px;
}
}
It seems it’s ok. I have modified a pre-existing rule
/**
* Titolo cat.su cell.
*/
@media only screen and (max-width: 769px){
h1.page-title{ font-size: 18px !important;
}
}
