sidebar menu which scrolls down in sidebar : <p>i saw this several times on other sites but wasnt able to find how to do it easily.</p>

<p>I have a website with a submenu in the left sidebar, now i want the menu-widget to stick inside the sidebar area at top of window when i scroll down, so the menu comes with down. </p>

<p>After reaching the end of the sidebar-area it should leave at the end and waiting to scroll up or refresh the site. When scrolling up it should stop at the top sidebar-area border.</p>

<p><code>For better understanding:</code>
<a href="https://jsfiddle.net/6hrsod07/" rel="nofollow noreferrer">https://jsfiddle.net/6hrsod07/</a>
i want the red menu scrolling with down inside of the light red area.</p>

<p>Thank you very much in advance!</p>
