Header fixed (sticky) but with decrease of size on roll

[NinaTaz]

Hi all,

 

i´m searching for 2 days to find a solution but i could not find it.

 

I could easy find the fixed header and it works, but i need when roll the page it shows a reduced version of the header.

 

Just like the Prestashop forum here, it shows a full version of the header when you are on top of page, but when you roll the page it shows a smaller version of the header.

 

How could i do it?

 

Thanks

Edited April 11, 2015 by NinaTaz (see edit history)

[NinaTaz]

Any one could help me? I´m sending a picture to show what i mean.