[Theme: Harmonic] Mobile Responsivness Broken

For the record it went through the custom CSS and did a trial and error removal. It appears the culprit was

section {
    height: 200px;
    min-width: 768px;
}

See also: https://www.linkedin.com/grp/post/154024-6016297093092687874

Yes, you can’t really set the width of an element like that if you want it to be responsive. Or, what you can also do is add a media query to reset the min-width to a lesser value when the screen width falls below a certain width.

Glad you found the culprit in your custom CSS – thanks for coming back and letting us know what the issue was. As CrouchingBruin mentioned, if you wrap that CSS declaration in a media query to restrict it only to larger screens (say, above 768px wide), that could be one workaround.

You can learn more about using media queries that target certain screen sizes here:

https://en.support.wordpress.com/custom-design/custom-css-media-queries/
https://css-tricks.com/snippets/css/media-queries-for-standard-devices/
https://webdesignerwall.com/tutorials/responsive-design-with-css3-media-queries