In this case, all the animations are delayed by 50 ms.
After that, list items begin to appear.
Each list item’s appearance is delayed by 50 ms after the 
previous list item begins to slide in.
Each list item takes 250 ms to slide from right to left.
After the last list item begins to slide in,
the button at the bottom waits another 150 ms to pop in.
The button animation takes 500 ms.

With each delay and animation duration defined,
the total duration is calculated so that it can be
used to calculate the individual animation times.

The desired animation times are shown in the following diagram: