Coding to make cover page different for Mobile and Desktop version

Site URL: https://www.autocars.ltd/landing-page-mini-2

Hi, i'm creating a cover page and i think it looks good on desktop. however the mobile version has a slight issue because the words are unreadable due to the background image (IMAGERY?)
This is how it looks like now:
Desktop:
Mobile:



I would like to know if there is any way to code and make the opacity of the overlay on the mobile version higher, so that I can read the words more clearly? something like this:


Currently im adjusting the overlay colour on top of my background image to play with the opacity level of the background image.

Add to Home > Design > Custom CSS

@media screen and (max-width:640px) {
.scrim {
    background: rgba(0,0,0,0.75) !important;
}
}

Thanks tuanphan for the solution! When i preview it on squarespace preview (desktop and mobile version), it works nicely. However when I tried viewing on the actual domain on the phone, it didn't work for my case (i think because CSS doesn't work on cover page). Nonetheless thanks for your help, I think I will try to create a new page instead of using a cover page!

20 hours ago, JamieC said:

Thanks tuanphan for the solution! When i preview it on squarespace preview (desktop and mobile version), it works nicely. However when I tried viewing on the actual domain on the phone, it didn't work for my case (i think because CSS doesn't work on cover page). Nonetheless thanks for your help, I think I will try to create a new page instead of using a cover page!

Try adding this to Cover Page Settings > Advanced > Header

<style>
  @media screen and (max-width:640px) {
.scrim {
    background: rgba(0,0,0,0.75) !important;
}
}
</style>