style:Uppercase to lowercase overflow-X

[soilSpoon]

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
• 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

Update overflow-Xto overflow-x

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

[stale]

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!

[stale]

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!