Examples panel is not scrollable

[rtoal]

Love the new layout.

When there are many examples, I was hoping to scroll them with the trackpad, but the panel does not scroll.

Adding overflow: scroll to #exampleContainer gives the expected behavior. The add-example popup scrolls with it, though, too, so if you are scrolled to the bottom of the examples, the add-example popup will be invisible, so maybe that needs to act more like a modal.