Language / page language attribute(s)

URL: /
Criterion: 3.1.1 Language of the Page (A)

The document language must be declared using the lang attribute on the HTML element. This allows the text-to-speech software to provide an appropriate rendition of the content.

I intend to add a lang attribute to the HTML element such that it matches the active language (not locale).

I expect this to apply to every page on Indico if done using a base template.