How to use:
Wait for the Print button to become active (all QR codes loaded), then click it.
Choose your printer, or choose "Save as PDF" to send to a print shop.
Cut along the dashed lines and stick one on each table.
In the print dialog, turn OFF "Headers and footers".
Otherwise the page number and web address take up space and can push cards
onto the next sheet.
Print one page first and scan it with your phone before running off
the whole set — paper and ink can defeat a code that looks fine on screen.
If you see QR errors below: the server needs the qrcode library —
run pip install qrcode pillow and restart.