Document st.bottom in API reference and cheat sheet (#1473)

* Document st.bottom in API reference, menu, and cheat sheet.

Add Bottom RefCard with screenshot on layout and main API index pages,
menu entry, cheat sheet example, and layout API page. Excludes
streamlit.json docstring updates.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Write st.bottom API page as manual docs like st.sidebar.

Replace Autofunction with prose on chat input pinning, sticky footer,
and main-area-only usage.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Johannes Rieke <johannes.rieke@gmail.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 3 people

content/develop/api-reference/_index.md

@@ -1610,6 +1610,19 @@ st.sidebar.write("This lives in the sidebar")
 st.sidebar.button("Click me!")
 ```
 
+</RefCard>
+<RefCard href="/develop/api-reference/layout/st.bottom">
+
+<Image pure alt="screenshot" src="/images/api/bottom.jpg" />
+
+<h4>Bottom</h4>
+
+Display items at the bottom of the window.
+
+```python
+st.bottom.chat_input("Say something")
+```
+
 </RefCard>
 <RefCard href="/develop/api-reference/layout/st.space">
 

content/develop/api-reference/layout/_index.md

@@ -116,6 +116,19 @@ st.sidebar.write("This lives in the sidebar")
 st.sidebar.button("Click me!")
 ```
 
+</RefCard>
+<RefCard href="/develop/api-reference/layout/st.bottom">
+
+<Image pure alt="screenshot" src="/images/api/bottom.jpg" />
+
+<h4>Bottom</h4>
+
+Display items at the bottom of the window.
+
+```python
+st.bottom.chat_input("Say something")
+```
+
 </RefCard>
 <RefCard href="/develop/api-reference/layout/st.space">
 

content/develop/api-reference/layout/bottom.md

@@ -0,0 +1,66 @@
+---
+title: st.bottom
+slug: /develop/api-reference/layout/st.bottom
+description: st.bottom inserts a pinned container at the bottom of the app, perfect for chat inputs, toolbars, and persistent controls.
+keywords: st.bottom, bottom, pinned container, sticky footer, chat input, toolbar, persistent controls, streamlit bottom
+---
+
+## st.bottom
+
+`st.bottom` is a layout container pinned to the bottom of the main app area. Use it for chat inputs, toolbars, footers, and other controls that should stay visible while users scroll through your app content.
+
+Elements can be passed to `st.bottom` using object notation and `with` notation.
+
+The following two snippets are equivalent:
+
+```python
+# Object notation
+st.bottom.[element_name]
+```
+
+```python
+# "with" notation
+with st.bottom:
+    st.[element_name]
+```
+
+<Important>
+
+`st.bottom` is only available in the **main app area**. Using it inside [`st.sidebar`](/develop/api-reference/layout/st.sidebar), [`st.dialog`](/develop/api-reference/execution-flow/st.dialog), or event containers (such as [`st.toast`](/develop/api-reference/status/st.toast)) raises an error.
+
+</Important>
+
+## Keep chat input at the bottom
+
+[`st.chat_input`](/develop/api-reference/chat/st.chat_input) behaves differently depending on where you call it in your script. At the **base level** of your app (the main area, not inside another container), the chat input appears at the bottom of the app automatically.
+
+If you call `st.chat_input` **inside a container**, it renders **inline** in that container instead. For example, `st.expander("Settings").chat_input(...)` places the input inside the expander, not at the bottom of the viewport.
+
+Use `st.bottom` to force the chat input to the bottom in those cases:
+
+```python
+import streamlit as st
+
+tab_chat, tab_logs = st.tabs(["Chat", "Logs"])
+
+with tab_chat:
+    st.write("Chat history goes here.")
+    st.bottom.chat_input("Ask a question")
+
+with tab_logs:
+    st.write("Log output goes here.")
+```
+
+## Add a sticky footer
+
+Use `st.bottom` for footers, toolbars, or status bars that should remain visible at the bottom of the viewport:
+
+```python
+import streamlit as st
+
+st.title("Dashboard")
+st.line_chart({"sales": [10, 20, 15, 30, 25]})
+
+with st.bottom:
+    st.caption("© 2026 My Company · All rights reserved")
+```

content/develop/quick-references/api-cheat-sheet.md

@@ -182,6 +182,16 @@ with st.sidebar:
 
 <CodeTile>
 
+#### Add elements to bottom
+
+```python hideHeader
+st.bottom.chat_input("Say something")
+```
+
+</CodeTile>
+
+<CodeTile>
+
 #### Columns
 
 ```python hideHeader

content/menu.md

@@ -398,6 +398,8 @@ site_menu:
     url: /develop/api-reference/layout/st.popover
   - category: Develop / API reference / Layouts and containers / st.sidebar
     url: /develop/api-reference/layout/st.sidebar
+  - category: Develop / API reference / Layouts and containers / st.bottom
+    url: /develop/api-reference/layout/st.bottom
   - category: Develop / API reference / Layouts and containers / st.space
     url: /develop/api-reference/layout/st.space
   - category: Develop / API reference / Layouts and containers / st.tabs