fix: overflow-X to lowercase

[xjh22222228]

Please check if the PR fulfills these requirements

• [ ] It's the right issue type on the title
• [ ] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• [ ] The commit message follows our guidelines
• [x] Tests for the changes have been added (for bug fixes/features)
• [ ] Docs have been added/updated (for bug fixes/features)
• [ ] It does not introduce a breaking change or has a description of the breaking change

Description

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Thank you for your contribution to TOAST UI product. 🎉 😘 ✨

[stale[bot]]

This issue has been automatically marked as inactive because there hasn’t been much going on it lately. It is going to be closed after 7 days. Thanks!

[coeing]

Please merge this, the warning distracts from more important warnings :)

[stale[bot]]

This issue has been automatically marked as inactive because there hasn’t been much going on it lately. It is going to be closed after 7 days. Thanks!

[coeing]

This merge should be a no-brainer as it should not destroy anything, but just removes the warning that distracts from other, more important warnings :)

[stale[bot]]

This issue will be closed due to inactivity. Thanks for your contribution!

[extempl]

Is tui editor abandoned?