[selfmodruntime]

No. Tablets and Phones do not have window managers. Also, a well defined side margin is not a "bad web trick" but an idea that's as old as print media, perhaps even as old as just written documents.

[prmoustache]

Have you opened aforementionned link on a smartphone? I did and it renders well.

Plain text is responsive by design.

Also the browser on my phone allow me to dial font sizing in 3 seconds.