diff --git a/browser/themes/windows/browser.css b/browser/themes/windows/browser.css
index 587e189d9c403c01463c4167de8c21d3533351cb..5edbc05b905692b29c9e292533616c9bc03cb5fe 100644
--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -31,7 +31,6 @@
     /* stylelint-disable-next-line media-query-no-invalid */
     @media -moz-pref("widget.windows.mica.toplevel-backdrop", 2) {
       /* For acrylic, do the same we do for popups to guarantee some contrast */
-      background-color: light-dark(rgba(255, 255, 255, 0.6), rgba(0, 0, 0, 0.6));
     }
 
     /* Using a semitransparent background preserves the tinting from the backdrop.
@@ -63,7 +62,7 @@
 
 /* This is needed for Windows 10, see bug 1961257 */
 @media (-moz-windows-accent-color-in-titlebar) {
-  :root[customtitlebar][sizemode="normal"] #navigator-toolbox {
+  :root[customtitlebar][sizemode="normal"] #browser {
     border-top: 0.5px solid ActiveBorder;
     &:-moz-window-inactive {
       border-top-color: InactiveBorder;
