small visual improvement for "modal-on-modal" edge case

Author: eug3nix

pgmanage/app/static/pgmanage_frontend/src/assets/scss/themes/dark.scss

@@ -389,6 +389,7 @@ SOFTWARE.
   }
   .modal-content {
     background-color: #2F3136;
+    box-shadow: 0 0 200px rgba(0, 0, 0, 0.5);
   }
   .modal-footer {
     border-top-color: #484a55;

pgmanage/app/static/pgmanage_frontend/src/assets/scss/themes/light.scss

@@ -354,6 +354,7 @@ SOFTWARE.
   }
   .modal-content {
     background-color: #FFF;
+    box-shadow: 0 0 200px rgba(0, 0, 0, 0.2);
   }
   .modal-footer {
     border-top-color: #d2d2d2;