Changing scroll distance in AJAX portfolio grid

Hi there,
I have a page that features a sticky submenu and a portfolio grid that opens individual items as an AJAX portfolio. Because of the sticky submenu, the scroll up to display the portfolio item cuts off the item’s container.
I initially used the code below to try and address the issue, but don’t like the white space it leaves above the container if a user scrolls back up the page.

#team .portfolio_preview_container.open_container {padding-top: 75px;}
#team .ajax_controlls.iconfont {
    padding-top: 75px;
}

Do you have any other suggestions that I can try to stop the container from being cut off by the submenu after opening? Is there a theme file I should try editing?
Thank you!