I would like to have a medium gray variable by default. 

Hexidecimal is base 16, meaning there are 16 values from 0 through F. We currently provide two values for grays:
```scss
 $dark-gray: #333;
$light-gray: #DDD;
```
Dark-gray is the 4th stop away from black. Light gray is the 3rd stop away from white. See the visual below:
```
0 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - A - B - C - D - E - F
# - # - # - ^ - # - # - # - # - # - # - # - # - # - ^ - # - #
```
To get equal gray values within the spectrum, sass calculated the following values:
```scss
 $dark-gray: lighten(#000, 25%) = #404040
  $med-gray: lighten(#000, 50%) = #808080
$light-gray: lighten(#000, 75%) = #BFBFBF
```

I think we should provide the 3 hex values I calculated above. 

The values are actually pretty close to the existing ones:
![Screen Shot 2013-03-22 at 3 37 14 PM 1](https://f.cloud.github.com/assets/339967/292484/044b1e52-9328-11e2-9559-cbcd21b4863c.PNG)