Fix a few bugs in the handlebars logic
Fix a few bugs in the handlebars logic

* Put the generated CSS inside a `<style scoped>` block
* Give class names to the sections that render fonts/grid rules
so that they can be updated on the client.

weigang992003/pure-css-chinese,yahoo/pure-site,jamesalley/pure-site,weigang992003/pure-css-chinese,yahoo/pure-site,jamesalley/pure-site