I cannot propose you the complete UI. But i can give you some brevity tips.
At first, you have to check what will the contents of most stairs (aka user's responses)
- if it's mostly like tech-user-forums, each response will be
-- mostly text (opinion and/or code snippet),
-- occasionally image or snapshot. And,
-- user's signature(...)
You can easily strip off signature. And visually compress the UI to only meaningful response like this.
SUBJECT .. .. .. .. .. .. PageNav
Date.Time UserX response snippet .. details link
Date.Time UserY response-reply snippet .. detail's link
Date.Time UserZ response-reply snippet .. detail's link
Date.Time UserX response-reply snippet .. detail's link
Date.Time UserX response-reply snippet .. detail's link
SUBJECT PageNav
There should be no gap between the lines
UserX name can have some subscripted rank indicator (colored depending on rank)
if consecutive responses have same date, then date should be omitted for subsequent response.
button can be something like "..." & on-click should pop open the response details text and image link
response-reply snippet text color can be gradient-ed from black to grey for added clarity.
The pageNav button can be very intuitive e.g. Like time selector on Android alarm app
