Can't overwrite css code

I have found that there is a piece of code in the generatepress that I can't seem to overwrite Pleas help. End goal is to have the footer element for the below screensize the same as desktop and mobile.

@media (min-width:600px) and (max-width:781px) {
.wp-block-column:not(:only-child) {
flex-basis:calc(50% - 1em)!important;
flex-grow:0
}
.wp-block-column:nth-child(2n) {
margin-left:2em
}
}

website is http://www.seedhaus.com.au/