Streamlit layout

How you structure your app affects usability more than you think.

Sidebar: navigation + global filters only

The sidebar should only contain navigation and app-level filters. Main content goes in the main area.

# GOOD
with st.sidebar:
    date_range = st.date_input("Date range")
    region = st.selectbox("Region", ["All", "US", "EU", "APAC"])
    st.caption("App v1.2.3")

# BAD: Too much content in sidebar
with st.sidebar:
    st.title("Dashboard")
    st.dataframe(df)  # Don't put main content here
    st.bar_chart(data)

What goes in sidebar:

• Global filters (date range, user selection, region)
• App info (version, feedback link)

What stays out:

• Main content, charts, tables, results

Columns: max 4, set alignment

Don't use too many columns, they get cramped.

# GOOD
col1, col2 = st.columns(2)

# Custom widths (ratios)
col1, col2 = st.columns([2, 1])  # 2:1 ratio

# OK with alignment
cols = st.columns(4, vertical_alignment="center")

# BAD: Too many, cramped
col1, col2, col3, col4, col5, col6 = st.columns(6)

Horizontal containers for button groups

Use st.container(horizontal=True) instead of columns for button groups:

with st.container(horizontal=True):
    st.button("Cancel")
    st.button("Save")
    st.button("Submit")

Aligning elements

Use horizontal_alignment on containers to position elements:

# Center elements
with st.container(horizontal_alignment="center"):
    st.image("logo.png", width=200)
    st.title("Welcome")

# Right-align elements
with st.container(horizontal_alignment="right"):
    st.button("Settings", icon=":material/settings:")

# Distribute evenly (great for button groups)
with st.container(horizontal=True, horizontal_alignment="distribute"):
    st.button("Cancel")
    st.button("Save")
    st.button("Submit")

Options: "left" (default), "center", "right", "distribute"

Bordered containers