Such a simple concept, executed perfectly. I don't play a huge number of puzzle games, but I didn't really enjoy this; I think it's probably because it's physics based!
The last couple of levels were definitely quite challenging and took a decent amount of trial and error, but got there in the end!
N.b. on the resizing issue, Firefox worked perfectly and it scaled up to my monitor. I don't know if monitor resolution has an impact, but I'm just on 1080p.
The music and audio is nice and works well, perhaps there could be a little juice on the marbles, but it's a pretty minor thing. I do agree with another commenter that I would have loved a restart button that maintained my current line setup, but maybe that would have trivialised the game too much by allowing fine tuning on a line-per-line basis.
I enjoyed this, and probably spent close to an hour playing! Thank you.