The `_bootstrap3` file is our bootstrap theme, so any of the variables declared in this file should be [bootstrap-specific](http://getbootstrap.com/customize/#less-variables). (Basically, we've got this pattern: https://github.com/twbs/bootstrap-sass#sass, third paragraph down, "You can override these by simply redefining the variable before the `@import` directive, e.g....") Anything below the variables should be an override of a bootstrap-specific style, so those would have to go below the bootstrap import. So the bootstrap file should look like this:

```
$brand-primary: #0075C4;
// ...
$font-family-sans-serif: "Helvetica Neue", Roboto, Helvetica, Arial, sans-serif;

@import "bootstrap-sass/lib/bootstrap";

// Fonts
@font-face { /* ... */ }
// ...
```

As far as how LESS/SASS work internally, I hear you, I haven't seen too much in their documentation about this and haven't really dug in to see. All I'm going by so far is just experience and the GitHub page for bootstrap-sass.