CSS to set Font size for Styled list in mobile phone

[Jean-Louis]

Hi,
I’m trying to change the font size of my styled list for mobile phones in the custom CSS of my page but I can’t make it work.
I tried for instance

@media screen and (max-width: 768){
ul li {
font-size: 10px !important;
}
}
or

@media screen and (max-width: 768){
.fa-ul li {
font-size: 10px !important;
}
}

and a number of similar coding, but that didn’t help!
Could you tell me what I should do?

the list is on the front page of my website : https://thailanguagechiangmai.com/wp/
Thanks a lot!