Consider using Roboto Mono instead of Courier New for code display

[chpapa]

Used by Firebase doc, Suggested by @mayyuen318

[chpapa]

@tensiuyan @rickmak @cheungpat @ben181231 @b123400 @david90 @bensonby thoughts?

[rickmak]

Honestly, I think the choice of font need professional knowledge. Which I don't have much insight. For profession input, loop in frnak. Follow is my 2 cent.

From user point of view, choice of font weight, spacing and size within a font family matter more. Even more than the choice of Font-family.

So a sensible point to start with is: why you think firebase doc is more readable?

For me, the biggest problem of existing code display is font-weight too light.

[tensiuyan]

In the coming doc site minor UI updates (ref#516), we will update the font family as well. We've used Lato in the design (which is the same as the one we use in the portal). Feel free to give comments: https://projects.invisionapp.com/share/FHBE4OAD8#/screens/230045331

[mayyuen318]

@tensiuyan I have commented on InvisionApp. I asked Siutao to bold a few words in the first paragraph and see the difference between bold and not bold. A bit feel like all the words are bold. Though @rickmak might think this font weight is great?

I checked the font - 16px, bold & regular on Google Font
It looks fine. Just dunno why it doesn't like very good on InvisionApp ><
Let me wait for Siutao's update.

[rickmak]

If you really ask me to comment.... I think the letter spacing and line spacing need to be adjusted. Not the font. The font looks fine to me.

The top margin and the bottom margin of code box away from text is different....