change css breakpoints

Hi

I have installed Storefront 2.3.4 and I need to change the css breakpoint.
I tried this but it doesn’t work.

add_filter('woocommerce_style_smallscreen_breakpoint','woo_custom_breakpoint');
function woo_custom_breakpoint($px) {
  $px = '800px';
  return $px;
}

I really want to avoid reprocessing all the sass. Is this possible ?
Thanks

[ Please do not bump. ]