Option to make Riot Webclient available on matrix subdomain

[danptr]

Is there an option to make the Riot Webclient available on matrix.domain.org instead of riot.domain.org. Since the default "It works! Synapse is running" isn't really needed on the matrix subdomain, port 80/443 should theoretically be available to be used by Riot, right?

[aaronraimist]

Riot should never be run on the same domain as Synapse because it could allow for XSS attacks. element-hq/element-web#1977