the problem comes from a CSS rule in your template.css. I played around with the
CSS rules affecting img's (including the map tiles), and if i disable the
"width: 100% !important;" rule than the map tiles stay visible even when the width
is less than 800 px.
Fixing this can be a bit tricky, you basically have two options:
- disable the rule in the template.css (like i did), but this may give problems in other parts of the template
- enter a rule in your custom.css that is more specific and overrides the rule in the template.css
I'm not much of an expert in css so i can't give you a ready-made solution here,
but i hope this will point you in the right direction.