I'm testing it and it seems it has trouble being responsive. Things get misaligned and text gets cut off.
Are we able to customize editor code?
Thank you for your question!
You have 2 opportunities to make your website responsive:
1) Create different versions for each device: Wide, Desktop, Tablet, Phone. Choose one of them and start create your responsive version for it.
2) Use Auto Layout option. Absolute website (without grids) becomes responsive without any additional actions (nobody has this feature over the Internet right now)
If you will have more questions, create a ticket in Site.pro system here: https://site.pro/Tickets/