Check out example codes for "elementor custom css for mobile". It will help you in understanding the concepts better.

Code Example 1

/*For browser/screen widths less than 768px*/
@media screen and (max-width: 768px) {
    .container {
        max-width: 100%;
    }
    .content {
        width: 100%;
    }
    .sidebar {
        width: 100%;
    }
}

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