White / empty section

Hi support,

I am trying to hide three elements on screen above 768px with the following code:

@media only screen and (min-width: 768px) {
.frontpage-layerslider-text-mobile {
display: none!important;
}}

All three elements have “frontpage-layerslider-text-mobile” added in the Custom Css Class.
The elements are: 1/1 column, a text block, and a button.

The elements are not visible, but a white, empty section is shown:

PS – I have tried with marking hide on large and medium screens in Screen Options.

Hope you can help :-)