determine size of outer element
function _getOuterSize(gridSize, sizeScreen) {
  if ('lg' === sizeScreen) {
    if (gridSize && gridSize.lg) {
      return gridSize.lg;
    }
    else if (gridSize && gridSize.md) {
      return gridSize.md;
    }
    else if (gridSize && gridSize.sm) {
      return gridSize.sm;
    }
    else if (gridSize && gridSize.xs) {
      return gridSize.xs;
    }
  }
  else if ('md' === sizeScreen) {
    if (gridSize && gridSize.md) {
      return gridSize.md;
    }
    else if (gridSize && gridSize.sm) {
      return gridSize.sm;
    }
    else if (gridSize && gridSize.xs) {
      return gridSize.xs;
    }
  }
  else if ('sm' === sizeScreen) {
    if (gridSize && gridSize.sm) {
      return gridSize.sm;
    }
    else if (gridSize && gridSize.xs) {
      return gridSize.xs;
    }
  }
  else if ('xs' === sizeScreen) {
    if (gridSize && gridSize.xs) {
      return gridSize.xs;
    }
  }
  // default
  return grid;
}