browser compatibility issues between Chrome Mac and PC – locks up during live

I maybe screwed up – I purchased this site for a new dev. site for a client, foxtrxdev4.com – this theme though functionally looks like it would work well
for my client – it’s technical train wreck –
You can not use lived edit – column widths and padding are different between Chrome Mac and PC.

I fear that it will not work on WP 4.9.3 that I’m on or PHP 7.0 – is this correct?

Please issue refund to my Envato Market account if this is the case – I have already wasted many hours in trying to make this worth.

Why is this still for sale?

Thank you!

Ticket