The review banner animation code has been the same for a long time. We

used jQuery's slideIn/slideOut functionality, which wasn't really the

best visual. It slid the bottom of the banner up over the contents,

rather than sliding the banner itself out of view. It also just wasn't

particularly fast or smooth.
We now use CSS transitions for this instead. The banner starts off in a

non-animated state and is positioned above the page. If there's an

existing draft when loading the page, the banner will be positioned at

the very top of the page, but within the page flow (without using

position: fixed) instead of docked to the top of the viewport. Only

when the JavaScript for the banner is set up will animations be enabled

and the banner set to be docked.
We then animate the max-height/height for the spacer used to push down

the page along with the transformY of the banner itself when

showing/hiding the banner.
The resulting animation is smoother, as the browser can be smarter about

how it handles the animations and resulting layout, and it's also a

better visual since the entire banner slides in/out of view rather than

the bottom edge.
It's worth noting that older browsers that don't support transitions won't

see animations here, whereas in the past they would. Instead, they'll see

the banner simply appear or disappear.

Tested in Firefox, Chrome, and Internet Explorer 9, 11, and Edge.
Tested creating a new draft, discarding/submitting a draft, and

loading the page with/without there being a draft.