A bookmarklet that removes these nasty overlays from websites that would work perfectly fine without a login, but still want you to create one. Create a new bookmark and paste the script source as the URL. (Use "Raw" to see only the script source for easy copy-paste.) When on a page with a blocking overlay click the bookmark.

no_blocking_overlay.js

javascript:(()=>{var d=document.documentElement,b=document.body,es=b.querySelectorAll("*"),m=20;for(var i=0;i<es.length;++i){var e=es[i];var s=getComputedStyle(e);if(s.position!=='static'&&s.position!=='relative'){var r=e.getBoundingClientRect();if(r.x<=m&&r.y<=m&&r.right>=window.innerWidth - m&&r.bottom>=window.innerHeight - m){e.remove();}}}var s='\n/**/;position:static!important;overflow:auto!important;width:auto!important;height:auto!important;';d.setAttribute('style',(d.getAttribute('style')||'')+ s);b.setAttribute('style',(b.getAttribute('style')||'')+ s);})();void(0)