Django website rendering as a total mess (intermittently, not always)

I have a website built in Django 1.5 that - at times - doesn't load correctly. And by not loading correctly, I specifically mean that if I type its url in my samsung s6 edge's mobile browser, I sometimes (but not mostly) see the page below. I am clueless regarding why this is happening (not much shows up in my logs), and how I can troubleshoot it. Please advise.