Icon box background color not working on mobile

Hello,

after searching for this in the forum, I was able to assign a color to a specific icon box on my website.

I added class “tutorialsiconbox” and then the following code in Highend Options:
.tutorialsiconbox .content-box {
background-color: #6797f5; /* Background color */
color: white; /* Text color */
border-color: #6797f5 /* Border color */
}

This worked great on laptop but when I checked the page (https://www.marcograssiphotography.com/tutorials/) on my phone I noticed that the background stayed white.

How can I fix this?

Thanks,
Jessica