Fix emoji width for small screen

I love your articles! I found broken emoji in articles when I read them on a smartphone. Thanks!

### Before
![emoji_before](https://f.cloud.github.com/assets/2177378/2026490/e9b0ea00-8894-11e3-9309-1b7a275f0662.png)

### After
![emoji_after](https://f.cloud.github.com/assets/2177378/2026491/eb353fca-8894-11e3-9b36-7fdec6699dbc.png)