Side bar is lag when scrolling?
<p>I just built my first <a href="http://ianxo.000webhostapp.com" rel="nofollow noreferrer">website</a> using flexbox.  but the sidebar seems to have a small problem on <strong>cellphone</strong>. I don't know how to explain it so I'm gonna post a screenshot.</p>

<p><a href="https://i.stack.imgur.com/ZKY1S.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZKY1S.jpg" alt="Screenshot"></a> as you can see there is a white space at the top-left corner. However it only happens in the first few pixels, if I keep scrolling the white space disappears. No problem <a href="https://i.stack.imgur.com/JnBzp.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JnBzp.jpg" alt="here"></a>.</p>