[fix] st.text_area negative height calculation #12891
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- Fix: Clamp calculated height to 0 minimum to prevent invalid CSS - Add comprehensive unit tests for negative height clamping - Add E2E snapshot test for height=10 case - Covers both visible and collapsed label scenarios
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sfc-gh-bnisco
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Oct 29, 2025
sfc-gh-nbellante
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Oct 31, 2025
…ments_test Skip on Chromium due to 1px snapshot width mismatch in CI. See failing workflow: https://github.com/streamlit/streamlit/actions/runs/18964912763/job/54180100557\n\nRecent snapshot touched by 9d3a016 (#12891); feature introduced in 5409b98 (#12848). We'll stabilize and re-enable later.
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Describe your changes
Fixes a bug in
st.text_areawhere very small height values would render larger than expected due to negative height calculations producing invalid CSS.Root Cause:
When calculating inner height, the formula
pixelHeight - labelAndPaddingcould produce negative values (e.g.,height=10with 30px label padding = -20px). Invalid negative CSS height values were ignored by browsers, causing the minHeight (68px) to take over, which madeheight=10render larger thanheight=30.Fix:
Added
Math.max(0, innerHeight)to clamp calculated heights to 0 minimum, ensuring all height values produce valid CSS.Note: the minimum height for
st.text_areais such that two lines of text fit in the input, so heights that would result in less space in the input will render as this minimum.GitHub Issue Link
Fixes #12867
Testing Plan
height=10caseContribution License Agreement
By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.