Twenty Ten: Details block having font-size issue in editor side

[nidhidhandhukiya]

Steps to reproduce the issue :-

1. Activate Twenty Ten theme.
2. Choose Details block.
3. Add some text.

You can able to see that hidden text font-size is different in editor side it is working fine in front side but editor side font-size is different.

[sabernhardt]

Front end: Details blocks with a paragraph inside, both in the post and in a widget area

[sabernhardt]

Post editor: Details block with a paragraph inside, displaying the summary text too small

[sabernhardt]

Widget editor: Details block with a paragraph inside, displaying the paragraph in the larger size used for post content

[sabernhardt]

The theme's (block) editor styles could be fixed, but I do not agree about decreasing the font size (or the line-height) of paragraphs in the Details block.

On the front end, the inner paragraph matches the font size of the summary:

• 16px in the main content area
• 12px in widgets

In the editor, the summary is 12px and standard paragraphs are 16px, whether you are editing a post or widgets. Twenty Ten's (Classic) editor stylesheet sets a body font size of 12px. Then it sets common elements to 16px: p, dl, td, th, ul, ol, and blockquote. As a result, the font-size discrepancy can happen with div elements too, including Button and File blocks.

Instead of trying to match font size one way in the post editor plus another way when editing widgets, I propose a smaller edit: updating the body size to 16px. It would not match the front for widgets, but I prefer that discrepancy over having the text so small in the editor (and elements such as paragraphs and lists have been larger in the widget editor since WordPress 5.8 introduced blocks for widgets).

• Increases font size for body, input and textarea elements in the editor, to match the #content area on the front.
• Updates the line-height to a unitless value.

In the post content area, the 16px font size also:

• Matches the front for elements that inherit the font size from body, such as summary in the Details block.
• Corrects div elements with relative font sizes, such as Button and File blocks.
• Corrects standard div elements within the Classic Editor.

Widget text is smaller than this on the front, but fixing that would be more complicated for little value (and it could be a follow-up effort _if_ it is worth doing).

Trac 62965