Pin input box to bottom of viewport so long responses don't force constant scrolling

Problem

When Claude generates a long streaming response, the viewport auto-scrolls to follow the latest tokens. If the response asks me a question or lists items I need to respond to, I have to scroll up to read them, then scroll back down to type — and as the response keeps streaming, the page keeps jumping. It turns into a constant fight with the scroll position.

This is especially painful when:

• The response contains clarifying questions that appeared earlier in the message
• The response lists multiple items I want to address one-by-one in my reply
• I want to draft my answer while still reading the response

Proposed solution

Pin the input box to a fixed position at the bottom of the viewport. Let the content area above it scroll independently — so I can scroll the response to a comfortable reading position, leave it there, and type my reply without the page jumping every time new tokens arrive.

In other words: input pinned, transcript scrolls under it. The same pattern most chat UIs already use.

Impact

Much smoother review-and-respond flow for long responses. Removes a small but constant friction point that adds up over a day of heavy use.