Reduce white space between header and content

I literally tried everything to reduce the space between header and content (above the ‘above’ section), which gets bigger as I am scrolling underneath):

tr {
  border: 3px solid white;
}

td {
  border: 3px solid white;
}

body {
  padding:0;
  border:0;
}

.single .hentry, .error404 .hentry, .page .hentry, .search-no-results .no-results {
  padding: 0 50px;
}

.site-navigation {
margin: 0;
}

#primary {
    margin-bottom: 0;
}

#content #infinite-handle {
    height: auto;
}

#masthead {
 margin-bottom: 0;
}

td#header {
padding-bottom: 0;
}

still, nothing works to eliminate that ugly white gap between the header and body.

My website is here: https://ubcmun.org/UBCMUN2017/

Any help with this is appreciated. Thanks!