Customize Capture Geometry Window

I'm using the HTML5 viewer within a frame of another online application we have and the frame the HTML5 viewer appears in is limited to 550px wide. Everything works fine, but when users start the capture geometry workflow, the popout frame consume 80% of the frame that the viewer is in. Which CSS/HTML files do I need to look at to find the tags that refer to this particular frame so that I can change the maximum width of the display capture geometry window?

 /customer/servlet/servlet.FileDownload?file=00P6000000e88M6EAI