http://iframe.eac.com.au/search/remote.aspx?src=http://www.thelentormodern.sg/holostyak-stb-2021

This is display.cgi (source). It takes some text you enter into a form, and displays it for you as HTML. This is a great way to see how some HTML code looks in your (or someone else's) browser. So paste 'n go: