Vaadin Valo page will not scroll

Question

I am creating a new Vaadin theme based on the native Valo theme. After updating to Vaadin 7.3 Valo (made by someone else), the contents of the page will no longer scroll. All other elements on the page where the overflow property is applied work fine, except for the whole page.

I know that I can apply this

.v-ui > .v-widget { overflow: visible; } 

which would be a "good" solution. But this is not something that can usually be seen after the update. What can cause this behavior? At the moment, no additional styles are used, only the native Valo.