SSRS design property InteractiveSize Width not working

Hi All,

I have report where in the visual studio design under report property I have set interactiveSize with 40cm,Height 0cm. PageSize property to 29.7cm X 21cm. However when I view the report on Web Browser Width doesn't change to 40cm. It always apply the page size. Is there any other setting I have missed. requirement is to have two different sizes for printing and HTML view.

Thanks