create centered_tab_label.css

chrome/centered_tab_label.css

@@ -0,0 +1,7 @@
+/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/centered_tab_label.css made available under Mozilla Public License v. 2.0
+See the above repository for updates as well as full license text. */
+
+.tab-label-container{ display: grid; justify-content: safe center }
+.tab-label,.tab-secondary-label{ overflow: hidden }
+.tabbrowser-tab[selected]:not(:hover) .tab-label-container,
+#tabbrowser-tabs:not([closebuttons="activetab"]) .tabbrowser-tab:not(:hover,[pinned]) .tab-label-container{ margin-inline-end: 7px }

html_resources/tagmap.json

@@ -136,5 +136,6 @@
 "window_control_placeholder_support.css":["window-control","patch"],
 "loading_indicator_bouncing_line.css":["status","navigation","effect"],
 "loading_indicator_rotating_image.css":["navigation","effect","status"],
-"menupopup_forced_color_schemes.css":["popup","colors","menu"]
+"menupopup_forced_color_schemes.css":["popup","colors","menu"],
+"centered_tab_label.css":["tab"]
 }

tags.csv

@@ -136,3 +136,4 @@ window_control_placeholder_support.css,window-control,patch
 loading_indicator_bouncing_line.css,status,navigation,effect
 loading_indicator_rotating_image.css,navigation,effect,status
 menupopup_forced_color_schemes.css,popup,colors,menu
+centered_tab_label.css,tab