LinuxQuestions.org - herbstluftwm + browser + full screen

Wasn't sure this was the correct section, but I am running Arch, so here goes.

I have a single 49" screen and using herbstluftwm I have set three tags using the following:

Code:

hc set_monitors 1280x1400+0+40 2560x1400+1280+40 1280x1400+3840+40

When I open my web browser on the middle tag (2560x1400+1280+40) and press F11 the browser obeys the left
most edge of the screen it is on, but then extends as though it is filling a 5120x1440 screen. The right side,
however, does not extend over the next screen but rather it appears to go under it

Is there a way I can let the browser know where the edge of my tag stops or perhaps find out how it
is calculating the full screen??

Happy to provide any other details as needed?