class ActiveAdmin::Views::Columns

def calculate_columns!
  span_count = columns_span_count
  columns_count = children.size
  all_margins_width = margin_size * (span_count - 1)
  column_width = (100.00 - all_margins_width) / span_count
  children.each_with_index do |col, i|
    is_last_column = i == (columns_count - 1)
    col.set_column_styles(column_width, margin_size, is_last_column)
  end
end