CRO Breaks Browsers In New and Interesting Ways

You can click on that “thing” to see what I can currently see in my browser when I try to use a public service website – namely the Irish Companies’ office (CRO)
It was working fine not so long ago, but an “upgrade” has broken it completely.
Seemingly it still works in Internet Explorer, but I don’t use Internet Explorer and have no intention of being forced to use it when I should have access to site like this.
How hard would it have been to write compliant HTML and test the site?
So who is to blame?
Was it a $random CRO employee or the website developers?
Answers on a postcard please ……….