(I'm reopening this ticket since the previous one was made private due to another costumer's interaction and the problem hasn't been solved yet)

I'm seeing that, even after removing the Topbar so that the header would always stay on top, it instead always makes an awkward "jump" when scrolling down with the mouse's scroll wheel.

Is there a way to prevent this?

It also happens with the live demos, for example:

http://pennews.pencidesign.com/pennews-game-news/

http://pennews.pencidesign.com/pennews-game-magazine/

Also seems to happen in some configurations of Soledad:

http://soledad.pencidesign.com/soledad-game-blog

But not in others:

http://soledad.pencidesign.com/soledad-videos-blog/

This:

.site-header, .penci-header-mobile {
    transition: all 0.5s;
    top: 0;
}

fixes the jump when scrolling down with the wheel, but now it does the jump when using the browser's scroll bar, which didn't happen before (using the scroll bar always showed the correct behavior).

It also does another strange jump when using the wheel and scrolling all the way to the top.

Going to Customize > Logo and Header Options then disable ticky header with "Disable sticky header" option turns it off, but rather than having to disable it, I think it would be better for everyone to fix it since it seems to affect both your PenNews and Soledad themes.