Recommendations for a stylish foldaway backpack

[ConstanzeMozart]

I need a foldaway backpack I can put in my one bag on the plane (flying Easyjet and refuse to pay for more than one bag!).
I've found a few very functional/outdoorsy-looking ones, but would ideally like one that's a bit more stylish, like Rains and those kind of stylish Nordic brands.
Any tips?
TIA

I’ve just bought a Nanobag daypack for this purpose, though stylish is not quite right… I have a small Roka pack which would probably fit the bill, but it’s a little bit bulkier?

Thank you. I looked at Nanobag, but I think the straps are too thin and not comfortable enough.
I should have said, I need wide and/or padded straps so I can carry it for quite a long time with heavy things like a full water bottle and a book in it.

Oh, forgot to say, I can’t find a Roka one; do you have a link?