Display size: large Font size: large
Changing these to small works as you describe. When they are set to large the close button is hidden behind the address bar at the bottom of the app window.
With text and window size at default the corners of the close button are barely visible and with great care you can tap it after a couple of tries.
Not sure where to look for xy resolution values.
That's odd because the image and its bottom div (that includes image title and close button) are set up to only fill the viewport.
Must have to do with your phone's resolution. (check android settings > display, and search for the screen resolution (HxV pixels)
1600x720
Ok, I'll give it a try and see if I can get that.
You're the very first reporting this.