#59960 - Replace em-based line-height with unitless values in CSS

[andbalashov]

This commit addresses ticket #59960, which identified issues with em-based line-height values in various CSS files within the WordPress Administration interface. Following the suggestion in the ticket, the em-based line-heights are replaced with unitless values while keeping their numeric value the same.

This change primarily affects the 'common.css' file but also includes updates in 'edit.css', 'install.css', 'list-tables.css', 'media.css', 'nav-menus.css', and the Thickbox styles. The update aims to enhance the consistency and scalability of the CSS and resolve issues particularly noted in iframe-based editors.

Referencing the follow-up to ticket #44643, this update aligns with the focus on coding standards and CSS improvements within the WordPress administration environment. By making line-heights unitless, we ensure better adaptability across different font sizes and display environments.

Files updated:

• wp-admin/css/common.css
• wp-admin/css/edit.css
• wp-admin/css/install.css
• wp-admin/css/list-tables.css
• wp-admin/css/media.css
• wp-admin/css/nav-menus.css
• Compiled Thickbox styles (thickbox.css)

Trac ticket: https://core.trac.wordpress.org/ticket/59960

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[mukeshpanchal27]

Thanks @andbalashov for the PR. The changes look good to me.

@sabernhardt could you please review it so we mark this ready for commit

[github-actions[bot]]

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Props andbalashov, mukesh27, sabernhardt.

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[github-actions[bot]]

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