Neat breakpoints for media() queries

gistfile1.txt

// Breakpoints.
$desktop:  new-breakpoint( min-width 960px 12 );
$tablet:   new-breakpoint( min-width 768px max-width 959px 12 );
$mobile:   new-breakpoint( max-width 767px 12 );
$handheld: new-breakpoint( max-width 959px 12 );