Edit your launch options in Steam. add --screen-fullscreen 1 --screen-width 1920 --screen-height 1080 changing the width and height values to match your screen resolution. And that will fix it.
Edit your launch options in Steam. add --screen-fullscreen 1 --screen-width 1920 --screen-height 1080 changing the width and height values to match your screen resolution. And that will fix it.