Fix Boostrap version inconsistency between v4 and v5. It seems CSS was v5 while JS was v4, resulting in the modal close button being visually broken. The fix required the modal to now have a fade animation as it would throw a JS error otherwise, but I hope that's not a problem.
Update timer and pause button values when changing configuration. Currently, one has to refresh the page to make those changes visible on the start buttons.
Change timer and pause config input to number type.