Add demo for standard mode

[egoist]

It could be placed at hackcss.com/standard.html

And the standard.css needs improvements too.

[sobolevn]

I am on it.

Should the demo link be styled the same as dark-mode?

[egoist]

If you mean this line https://github.com/egoist/hack/blob/master/src/html/index.jade#L18

I think you can simply update it to …dark mode and standard mode…, or if you have any better idea 😄

[egoist]

closed, thanks to @sobolevn 's work.