When overhauling teh HTML/CSS, I was primarily testing on PC, but also frequently testing on phone and tablet along the way (and occasionally other things liek terminal browsers, Raspberry Pi, and Windows XP too - I would have tested on TV as well if I had access to one that's less than 10 years old!). The same cannot be said for anyone who previously touched kokonotsuba - sans things that were changed at my suggestion

I'll be the first to admit it's not yet perfect (10"+ tablet in particular is still kinda awkward), but I strongly believe that a well-designed site should look good on any display without ghey compromises or an entirely different UI. A site that works poorly at various resolutions just has shitty HTML/CSS!

Making a site worse/unusable for mobile displays (either through neglect or active countermeasures) is just plain dumb - it doesn't keep out crappy users or bad actors, nor does it ever truly prevent mobile users from accessing the site (desktop view and user-agent spoofing exist). In the worst cases, it backfires entirely and prevents users with lo-res PC monitors from accessing the site (*cough* mootxico *cough)

All it really serves to do is limit the number of users frequenting a site, which is antithetical to Heyuri's various goals and purposes:
1. be the place to be
2. attract hawt girls
3. TOTAL INTERNET DOMINATION!!!1