[samyferhat]

Description

• Set position: fixed on .dialog:not([open]) in scss/_dialog.scss.
• The open states do not change. Modal, non-modal, and exit animation keep the same rules.

Motivation & Context

• .dialog sets display: flex so the exit animation works. Thus a closed dialog keeps its box.
• The UA sets position: absolute on a closed <dialog>. A tall closed dialog adds scrollable overflow, and the page shows a scrollbar.
• A fixed box does not add scrollable overflow to the page.
• Checked in Chromium with a long dialog after a button. Before: the page is 2594px tall and scrolls. After: 600px, no scrollbar. The positions of the open modal and non-modal dialogs are the same as before.
• npm run lint, npm run css-test, and npm run dist pass locally.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-43137--twbs-bootstrap.netlify.app/docs/6.0/components/dialog/

Related issues

Fixes #43128

🤖 Generated with Claude Code