Above there must be nine scalable child objects (blue circles) on a 3 by 3 grid, where each horizontal line (3 circles) must occupy 100% of the available width and each vertical line (3 circles) must have the same height as the width of a horizontal line (each circle occupies a square viewbox).
CSS settings: html and body elements are set to height:100%, the div height is not set, the object is set to height:33.33%.
This raster image screenshot shows the desired rendering.