Work around Chromium bug that gives false positives during accessibility pass (#7183)

Related to microsoft/accessibility-insights-web#692
Related to https://bugs.chromium.org/p/chromium/issues/detail?id=647594

Author: joelverhagen

src/Bootstrap/dist/css/bootstrap-theme.css

@@ -70,6 +70,10 @@ body {
   .container {
     margin-top: 50px;
     margin-bottom: 50px;
+
+    // This is a workaround for the following bug:
+    // https://github.com/microsoft/accessibility-insights-web/issues/692
+    background-color: @panel-footer-bg;
   }
 
   a {