--- a/devtools/client/performance/performance.xul
+++ b/devtools/client/performance/performance.xul
@@ -90,17 +90,17 @@
           <toolbarbutton id="import-button"
                          class="devtools-toolbarbutton"
                          label="&performanceUI.importButton;"/>
           <toolbarbutton id="clear-button"
                          class="devtools-toolbarbutton"
                          label="&performanceUI.clearButton;"/>
         </hbox>
       </toolbar>
-      <vbox id="recordings-list" flex="1"/>
+      <vbox id="recordings-list" class="theme-sidebar" flex="1"/>
     </vbox>
 
     <!-- Main panel content -->
     <vbox id="performance-pane" flex="1">
 
       <!-- Top toolbar controls -->
       <toolbar id="performance-toolbar"
                class="devtools-toolbar">

--- a/devtools/client/themes/widgets.css
+++ b/devtools/client/themes/widgets.css
@@ -468,16 +468,17 @@
   margin: 0;
   -moz-margin-start: 4px;
 }
 
 /* SideMenuWidget misc */
 
 .side-menu-widget-empty-text {
   padding: 4px 8px;
+  background-color: var(--theme-sidebar-background);
 }
 
 /* VariablesView */
 
 .variables-view-container {
   /* Hack: force hardware acceleration */
   transform: translateZ(1px);
 }