Embedding Vaadin in HTML looses all Styles

Lovely to see a reply so early.

I cannot share the page/project as its a huge project. A sample Vaadin application works perfectly fine. When I copied the code to existing Spring Application project, I realised that the Theme SCSS file settings are not picked up at all :(.

a) If I run the Vaadin Application URL in browser, it works perfectly fine with all style settings.
b) When I embed using a DIV tag, the Vaadin App opens correctly with default Valo settings. All custom settings are lost.
I checked whether Spring-security is blocking /VAADIN/* pattern, but it is not. The DIV tags for layout (slots) are not having Style classes as set in code using setStyleName().

The page I embedded Vaadin has bunch of other CSS styles loaded, so I was wondering whether HTML BODY level style is not overridden by Vaadin? Not sure.

Thank you,

Ananth