Fixed #33727 -- Fixed color contrasts in admin header.

django/contrib/admin/static/admin/css/base.css

@@ -946,8 +946,11 @@ a.deletelink:focus, a.deletelink:hover {
 #user-tools a:focus, #user-tools a:hover,
 #logout-form button:active, #logout-form button:hover {
     text-decoration: none;
-    border-bottom-color: var(--primary);
-    color: var(--primary);
+    border-bottom: 0;
+}
+
+#logout-form button:active, #logout-form button:hover {
+    margin-bottom: 1px;
 }
 
 /* SIDEBAR */

django/contrib/admin/static/admin/css/responsive.css

@@ -45,7 +45,6 @@ input[type="submit"], button {
 
     #branding h1 {
         margin: 0 0 8px;
-        font-size: 1.25rem;
         line-height: 1.2;
     }