Window size in X windows different from console

[pearmtn]

Hi, This might be a more general question about X windows and monitor resolution in Linux, but it’s related to my magic mirror so hopefully someone else has encountered and solved this issue:

I have set up a magic mirror (v2) on my pi zero running Jessie Lite. To do so I ended up following the advice of some others here on the forum and am using the kweb browser to display the MM through X windows. When I boot up my Pi Zero, the command line interface takes advantage of the full screen area (i.e. every line can take up the entire screen width and height). When I start X windows and kweb with default screen settings it only takes up about 2/3 of the screen in any direction. I would really like to use the full screen. It’s not the MM itself that’s the problem as any website I display will use the same amount of screen area. I’ve tried playing with the frame_buffer settings, but it doesn’t do what I would want (it seems to scale the image within the bounds I’m seeing, rather than expanding the bounds to the edge of the screen). I am connected by DVI using an adaptor to the mini hdmi port on my pi. Any advice on this would help.
Thanks!