While duckduckgo.com is using the standard HTML5 doctype, html.duckduckgo.com is using <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http:/

While duckduckgo.com is using the standard HTML5 doctype, html.duckduckgo.com is using <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> and lite.duckduckgo.com is using <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> Is this on purpose? To make the website work on older browsers?