When you scroll the slider so that the buttons are no longer on the current page and then try to drag the blue beyond the yellow, the lines move out of the field completely.
Expected behavior: shouldn't be able to drag blue past yellow.
See gif
Page where this can be reproduced
Present in
Chromium Version 58.0.3029.110 Ubuntu 16.04 (64-bit) Firefox Version 54.0 Ubuntu 16.04 (64-bit)