I've never had any problems viewing other Lemmy instances on mobile but this one is completely unusable. Even if you ignore the broken layout you can't even sign in. Is this a known issue from whatever frontend this community is using? Any word on when it might be fixed?
Looks like the CSS didn't load, I just checked programming.dev on my phone and it worked fine. Have you tried refreshing? Also, programming.dev uses the default front-end for now and no modifications have been implemented yet.