/* Transition the color nicely */
#progess-anim rect[data-prog] {
  transition: fill 280ms ease;
}

/* We use classes to animate fill (attribute-only changes won't transition) */
#progess-anim rect[data-prog]:not(.orange) { fill: #334E60; } /* blue */
#progess-anim rect[data-prog].orange       { fill: #B35C31; } /* orange */