After code injection to header, navigation bar won't display at the top

Site URL: https://www.libertypartnershr.com/career-page#!/search?page=1

Per my template, I am injecting code into one page only, with the only option to do so into the header. this is fine except I cannot get the Navigation bar to remain at the top of the page, it is pushed down below the content from the code injection...please help and thank you!

Add to Page Settings > Advanced > header

<style>
  header.Header.Header--top {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 999;
}
  div#jb--job-board {
    margin-top: 133.5px;
}
</style>

Thank you Tuan! That worked great!