Fix code being wrapped incorrectly

[crasm]

This should prevent code from being wrapped when displayed on the site. I'm not sure if it's just my font choices, but that ideally wouldn't affect the code wrapping. (Anyone else have this problem other than me?)

I've tested this in chromium and firefox by editing the css in-browser, but I wasn't able to test the actual changes to the sass file.

[rgson]

Some critique, quoted from #31 (comment)

#33 may well fix it in many cases, though the new number also seems rather arbitrary/unreliable. Unless I'm mistaken, em is determined by the height of the font (and not its width). If that's the case then 60 em is still not guaranteed to be wide enough.

The ch unit could possibly be used to get some level of guarantee. It's supposed to be the actual width of the character 0. In a monospace font it should thus be the actual width of all characters. However, there seems to be some compatibility issues with IE (http://caniuse.com/#feat=ch-unit). It'd also have to be applied to the code section of the page instead of to .container in order for it to measure the correct font.

Another alternative would be Javascript; to programmatically measure the width of a character and change the width of the code section to hold 80 of them. A reasonable default would of course be kept in the CSS as fallback.

[adambard]

LGTM, thanks!