Don't regard 1024px width viewport as mobile

Currently we treat 1024px as mobile in some places (e.g. `isMobile` in
nextcloud-vue) and as not mobile yet in others (e.g. in mobile.css).

This commit changes `mobile.scss` to treat viewports smaller than 1024px
as mobile.

This PR accompanies nextcloud-libraries/nextcloud-vue#3768

Both are required to fix
nextcloud-libraries/nextcloud-vue#3758.

Signed-off-by: Jonas <jonas@freesources.org>

core/css/mobile.scss

@@ -1,6 +1,6 @@
 @use 'variables';
 
-@media only screen and (max-width: variables.$breakpoint-mobile) {
+@media only screen and (width < variables.$breakpoint-mobile) {
 
 	/* position share dropdown */
 	#dropdown {