--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -160,24 +160,16 @@ panelview[mainview] > .panel-header {
 }
 
 .tabbrowser-tab:not([pinned]):not([fadein]) {
   max-width: 0.1px;
   min-width: 0.1px;
   visibility: hidden;
 }
 
-.tab-close-button,
-.tabbrowser-tab::after,
-.tab-background {
-  /* Explicitly set the visibility to override the value (collapsed)
-   * we inherit from #TabsToolbar[collapsed] upon opening a browser window. */
-  visibility: visible;
-}
-
 .tab-close-button[fadein],
 .tabbrowser-tab[fadein]::after,
 .tab-background[fadein] {
   /* This transition is only wanted for opening tabs. */
   transition: visibility 0ms 25ms;
 }
 
 .tab-close-button:not([fadein]),

--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -634,18 +634,17 @@
     </toolbar>
 
     <toolbar id="TabsToolbar"
              class="titlebar-color"
              fullscreentoolbar="true"
              customizable="true"
              mode="icons"
              aria-label="&tabsToolbar.label;"
-             context="toolbar-context-menu"
-             collapsed="true">
+             context="toolbar-context-menu">
       <hbox class="titlebar-placeholder" type="pre-tabs"
             skipintoolbarset="true"/>
 
       <tabs id="tabbrowser-tabs"
             flex="1"
             setfocus="false"
             tooltip="tabbrowser-tab-tooltip"
             stopwatchid="FX_TAB_CLICK_MS">