How can i change the style of the iframe and iframe content?

I need to have iframe content (report) to stretch inside the iframe. Now it has wide gray margins around it. Do i need to find a class of the div that containes the report and change it's style or there are some properties that i can set on the iframe? 

This is the div tag that has the margins:

<div class="displayArea disableAnimations fitToPage" explore-canvas-printer="" disable-print="" style="margin-left: -584px; margin-top: -337.625px; width: 1168px; height: 675.25px;">

Thank you!