My answer is less useful to the discussion. But here you go:

1. I wouldn't use GPLv3

2. I wouldn't care if people stole my code that I open sourced or if they tried to license it a different way.

3. I personally follow the license of others when using their code. I wouldn't steal GPLv3 code without proper attribution etc. That's their right.

All that doesn't go against my initial opinion: GPLv3 for a small micro blog templating system is lame. Enforcing it for a bit of CSS is petty.

> All that doesn't go against my initial opinion: GPLv3 for a small micro blog templating system is lame. Enforcing it for a bit of CSS is petty.

It is a matter of principle, probably?

Not the parent but your question and the implicit accusation is way too overblown. The design here is so generic that it can easily be used by tons of site out there. It's just a few lines of CSS here and there and if I have a design like that and come across something similar I would just chalk it up to someone with similar taste. Going out of your way to demand attribution for it is the very definition of petty.