A solution to your question would be:
#grve-page-anchor {
height: auto;
}There might be some issues with fixed, shrink, scroll up headers, etc. I guess this is why it requires a fixed height, but this is easy to find out just by testing.
To avoid any potential issues, you could wrap this code inside media queries of max-width 1023px, this is the width where the responsive header comes into play by default ( I guess ). So there won’t be any issues with the desktop headers.
