COMPASS/SCSS mixin for 2 column CSS layout

SCSS mixin: two-columns.scss

@mixin two-columns($prop1, $prop2, $col1 = '.main', $col2 = '.sub'){
  $totalwidth : $prop1 + $prop2;
  
  #{$col1} {
    @include column(ceil($blueprint-grid-columns * $prop1 / $totalwidth ));
  }
  #{$col2} {
    @include column(floor( $blueprint-grid-columns * (1 - $prop1/($prop1 + $prop2))), true);  
  }  
}

// usage:
@include two-columns(2,1);

// result: will generate CSS code for 2 columns: 
//   .main -> with 2/3 width of total width
//   .sub  -> with 1/3 width of total width