Co-authored-by: ntsekouras <ntsekouras@git.wordpress.org>
Co-authored-by: jorgefilipecosta <jorgefilipecosta@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

* Make footer a fixed height; add margin to modal content

* Remove Spacer from bottom of Library tab content

* Add variable for footer height size

Co-authored-by: mikachan <mikachan@git.wordpress.org>
Co-authored-by: creativecoder <grantmkin@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: jordesign <jordesign@git.wordpress.org>
Co-authored-by: matiasbenedetto <mmaattiiaass@git.wordpress.org>

…th `data-wp-on`. (#60661)

* Allow multiple event handlers for the same type

* Add simple test

Co-authored-by: DAreRodz <darerodz@git.wordpress.org>
Co-authored-by: felixarntz <flixos90@git.wordpress.org>
Co-authored-by: luisherranz <luisherranz@git.wordpress.org>

… deeply nested lists (#60845)



Co-authored-by: andrewserong <andrewserong@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: diggeddy <diggeddy@git.wordpress.org>

Co-authored-by: andrewserong <andrewserong@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>

* Layout: Always add semantic classes
* Default to undefined
* Feedback

Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: tellthemachines <isabel_brison@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>
Co-authored-by: colorful-tones <colorful-tones@git.wordpress.org>
Co-authored-by: ellatrix <ellatrix@git.wordpress.org>
Co-authored-by: davecpage <davecpage@git.wordpress.org>

… theme.json (#60764)

Co-authored-by: tellthemachines <isabel_brison@git.wordpress.org>
Co-authored-by: oandregal <oandregal@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: creativecoder <grantmkin@git.wordpress.org>

…ide sizes if no layout sizes exist (#60489)

* Layout: Skip outputting base layout rules that reference content or wide sizes if no content or wide sizes exist

* Update tests