Improve zoom button sensitivity in Cesium Stories

Moving this issue from https://github.com/CesiumGS/cesium-ion-community/issues/313.

With my mouse wheel I can effectively zoom toward and up against the terrain but no further. This is nice.

If I hit the ‘+’ navigation button above the ‘home’ icon I easily overshoot my target. It looks like the below following one press after a fresh start

Thanks for opening this issue, @RussellGrew. The on screen navigation buttons, especially + and - can certainly use some improvements. We’ll use this issue to track updates to that behavior. I don’t have a specific ETA, but hopefully we can make it work more like middle-mouse scrolling so that controls have a consistent “feel”

I’ve always found that moving the mouse wheel even just one wheel step can easily over shoot, like it’s going over 1 km per wheel step! I gotta hold the right button and move the mouse forward back to fine tune.