thoughtbot/bourbon — pull request #154 by Emerson (2012-12-18 21:13:00+00:00)
Title: Fixing calculation of flex-gutter and flex-grid functions

After trying to use the `flex-gutter()` and `flex-grid()` functions, I found that the width calculations were wrong. If you take the example in the comments of the [_flex-grid.scss](https://github.com/Emerson/bourbon/blob/master/app/assets/stylesheets/functions/_flex-grid.scss) file and run the numbers manually through the `flex-gutter()` and `flex-grid()` functions, you'll see that the result is incorrect (too big).

To confirm this problem:

* start a new rails app
* install bourbon
* create a basic 4-column flex layout, using the defaults from the docs or comments in the `_flex-grid.scss` file
* Notice that the columns don't work (they are too big).