Fix alert background colors

app/assets/stylesheets/framework/flash.scss

@@ -8,19 +8,19 @@
 
   .flash-notice {
     @extend .alert;
-    @extend .alert-info;
+    background-color: $blue-500;
     margin: 0;
   }
 
   .flash-warning {
     @extend .alert;
-    @extend .alert-warning;
+    background-color: $orange-500;
     margin: 0;
   }
 
   .flash-alert {
     @extend .alert;
-    @extend .alert-danger;
+    background-color: $red-500;
     margin: 0;
 
     .flash-text,
@@ -42,14 +42,16 @@
 
   .flash-success {
     @extend .alert;
-    @extend .alert-success;
+    background-color: $green-500;
     margin: 0;
   }
 
   .flash-notice,
   .flash-alert,
-  .flash-success {
+  .flash-success,
+  .flash-warning {
     border-radius: $border-radius-default;
+    color: $white-light;
 
     .container-fluid,
     .container-fluid.container-limited {