Changing line height on mobile only

Site URL: https://joeylim.xyz/art-dubai

Hello! 

I'm trying to change the line height for every text on my website when viewed on a mobile device. Currently, I've set the line height to 0.7em on the site style, but when viewing on a mobile device the lines overlap. 

I've found the code: 

@media screen and (max-width:767px) {
h4 {
    line-height: 1em;
}
}

but it's not working for me. Any ideas why? 

Try adding !important to the mobile query: 

@media screen and (max-width:767px) {
h4 {
    line-height: 1em!important;
}
}