Create me a website design for a split calculator website which helps people plan out pieces for erging, swimming, running. At the bottom there is a split pane which allows users to adjust the intervals length by sliding the split pane, change the split for that interval and delete it. there should also be buttons to add an interval, delete all of them, undo, redo and change the distanace of the piece. | A shadcn/ui and v0 generation - v0
