Netweaver Portal 7.3 - Rendering issues in Firefox & Safari

Hi,

We have recently upgraded our portal from 7.02 to 7.3. After the upgrade, we are facing issues with rendering of drop down buttons in UWL and also Substitution page date selection button. Please refer the below image from Mozilla Firefox browser.

Image may be NSFW.
Clik here to view.

The buttons appear correctly when opened in Internet Explorer.

Image may be NSFW.
Clik here to view.

Thanks,

Vijay