Please would you explain why adding ’ > slot’ fixed Issue: toolbarbuttons_in_tabs_periphery.css makes some tabs jump several by pixels when hovered, resizing of tabs is weird #419?

What underlying change in Firefox 131 made this necessary?

Similarly, why adding ’ > slot’ to the ‘scrollbox[orient=“horizontal”] selector’ also fixes this old tab-centering code broken by Fx131.0 update?

#tabbrowser-arrowscrollbox:not([overflowing]){ –uc-flex-justify: center; } scrollbox[orient=“horizontal”]{ justify-content: var(–uc-flex-justify,initial); }

CSS userstyle from OP YOUBESEENUMBA1’s post ‘Update 131.0 broke tab-centering code’: https://www.reddit.com/r/FirefoxCSS/comments/1fxb0wb/update_1310_broke_tabcentering_code/

(Note. Fedia’s codebox not playing… ‘#tabbrowser’ is always displayed as an unwanted circular link to this site?)

  • @MrOtherGuyM
    1•13 days ago

    Bug 1913322. That style requires the slot element to not have it’s own box - previously that was already the case since <slot>s have display: contents by default, but with that style that specific slot was given display: flex and thus have its own box. Thus, we remove it.

    Which reminds me, by making it have display: contents the tabs cannot overflow to scrollable box anymore. Instead they just overflow invisibly, which is no bueno.

    • ResurgamS13OP
      1•13 days ago

      Thanks for the info… hadn’t realised until digging around a few minutes ago that the ‘old tab-centering code’ mentioned by OP YOUBESEENUMBA1 (above) very likely originated from your own reply post here back in May 2023! :)