Sticky nav not working over page content

Hi im using this css

.secondary-navigation {
position: -webkit-sticky;
position: sticky;
top: 0px;
border-top: 3px solid #cecece;
border-bottom: 2px solid #cecece;
}

But it doesn't work. When i applied the same sticky css to top bar, it worked, but stops scrolling with the user when it hits the site content white part. The same css works on another site so its confused me abit, i remove overflow thing already incase it was that other css. But still no luck, Thanks.