Edit some features

[jarrekk]

Hi @cognitom ,

I have edited some places, maybe it will be helpful for you:

1. At Paper sizes in paper.css, I make paper at middle of screen to make it looks better.
2. I add class continuous to make paper display continuous if you want, so I can use wkhtmltopdf to make html page to pdf without page overflow.

Then I compress paper.css again.

Thanks