TYPO3 Core

This is a collection ticket for the improvements inside the EXT:styleguide

My Ideas:

• add a copy-icon for copying the example code
• add tabs for several code examples (Fluid, Lit, Plain JS, PHP)
• examples for infobox should include/exclude an icon
• improve the view of the example code
• add more examples to the Styleguide module like a multi-step-wizard

• add uuid example
• add json example
• Flash Messages have no example code, only the messages itself

• while saving the basics element, I get an error, that link_2 has a wrong format.

I haven't created issues for all of them. I will link them as sub issues as soon as they are created.