Twitter Bootstrap grid: Replace floats with inline-block display and add utility classes (.vertical-align-top, .vertical-align-bottom, .vertical-align-middle) for vertical alignment. Import file after Bootstrap imports.

_overwrite-floats.scss

// replace floats with inline-block
%set-inline-block {
  float: none; 
  display: inline-block; 
  margin: 0 -0.125em;
  vertical-align: top;
}

@mixin replaceFloatloop($class) {
  @for $i from 1 through 12 {
    .col-#{$class}-#{$i} { @extend %set-inline-block; }
  }
}

@each $size in xs, sm, md, lg {
  @include replaceFloatloop($size);
}

// vertical align utility classes
@mixin addVerticalAlign($pos) {
  .vertical-align-#{$pos} { vertical-align: $pos }
}

@each $pos in top, middle, bottom {
  @include addVerticalAlign($pos);
}