You actually don’t need this CSS, you already have similar CSS, but it’s under a media query: @media (min-width: 768px) {, which makes the CSS only works on desktop.
Try to find the CSS you added, add one more}at the end should fix the issue.
Thanks Ying, solved, but another problem appear, the title of the articles on the magazine grid appear now in black on mobile and i want it in white like in PC.
You’ll need to exam all your CSS, find out if there’s another missing } after each media query, or if the CSS should be included under a certain media query.