Add Scrollbars to Quick Launch

Add Scrollbars to Quick Launch

Note: If you just want to tighten up the Quick Launch area then see this article:http://techtrainingnotes.blogspot.com/2011/10/sharepoint-2010-365-tighten-up-quick.html
When you scroll down in a SharePoint page to find what's at the end of the Quick Launch area you also scroll the top navigation area out of site. This area has the site title, top link bar, search and the Tags and Notes buttons. To be able to browse the Quick Launch area without scrolling the entire page add this CSS to your master page:
.ms-quicklaunch-navmgr
{
    overflow-y:scroll;
    height:200px;
}
You will need to carefully select the height property and/or write some JavaScript to set the height based on the user's browser settings.
    
If you want to scroll the entire left navigation area then use this CSS:
#s4-leftpanel-content
{
    overflow-y:scroll;
    height:300px;
}
    
Setting the height of this area gives you a little bonus of adding text or links just below the navigation area. Search for "MSO_ContentTable" in your master page and place your content between the two "</div>" tags above this line. (This example is for the standard v4.master page. Yours may be different.)
    




Reference:
http://techtrainingnotes.blogspot.in/2012/06/sharepoint-2010fun-with-scrollbars.html