Power BI Embedded format for mobile

Followed this power bi embedded get started sample and noticed that the viewing of reports wasnt great on a mobile phone.  Therefore I created a PBIX file that targeted mobiles, summarising the data using cards and placing them on a Cortana (296 X 592) page.  The issue is the left grey padding around the page.  Is there a way to fix this?  I assume it's Power BI instead of the ASP web page setup?

What it looks like initially in mobile web browser, forcing the user to scroll before they can see the visualsWhat it should look like without the need for scrolling