If it was only for one particular site you could allways use the Create Application Shortcut option in the page icon at the top. You wont have any omnibar or stuff but maybe its usefull to you (the window can be alot smaller).

I find that the width is all most precisely half of the screen width.
Is your screen near 560 pixels, sarjoor?

Thanks PAEz!
It really works!!

Thanks everyone!

Hi Kuntakimp, I'm glad you have a solution that works for you. Again, I think your minimum width is being affected by the extensions you have installed.

BTW, my monitor screen size is 1152 x 864.