Fix formulas causing a scroll instead of breaking

[MoinJulian]

This pull request focuses on improving the display and styling of popup components and mathematical content in the application. The main changes are related to the structure and appearance of the popup's HTML content and better handling of line breaks in rendered math.

Popup component improvements:

• Wrapped the popup's dynamic HTML content in a new <div class="html"> to provide a dedicated styling hook and improve structure.
• Added a CSS rule for .html to enable vertical scrolling when the content overflows, ensuring better usability for long popups.

Math rendering enhancements:

• Added a .katex-break CSS class to allow proper line breaks and inline display for math elements, improving the readability of mathematical content.

[MoinJulian]

This is now basically the same functionality as the current deployed version
https://catdat.app/category/fld

[ScriptRaccoon]

The formulas still break. Also, there is a big redundant scrollbar now, also in the wrong direction (overflow-y: scroll should be overflow-x: auto, if at all).

But scrolling should be the exception; details here.

Screenshot from http://localhost:5173/category/walking_splitting:

The solution will not be straight forward, otherwise I would have already added the few lines of CSS. ;-)

[MoinJulian]

I will have another look at it tomorrow. I tried only breaking it at the = but that doesn't work because it isn't a distinct element and just part of the bin operators.

Just for clarification it should only allow breaking on = but in the best case always stay together in one line?

[ScriptRaccoon]

Let's address the XSS in a different PR, i.e. please remove 6ae3514 from this PR. (And please check out my comment at #146 before working on this.)

Just for clarification it should only allow breaking on = but in the best case always stay together in one line?

Yes. Maybe other relation symbols are also OK, like $\cong$. But tbh I have no idea if this is possible at all. I was only thinking out loud there.

[ScriptRaccoon]

Do you plan to continue working on this?