var topPos;
var updatedPos;
window.onscroll = navPos;
if (!topPos) {
  topPos = 124;
}
function navPos() {
  var pos = window.scrollY;
  if (!topPos) {
    topPos = 124;
  }
  var st = document.getElementById('navlinks');
  if (st) {
    if (pos < topPos && updatedPos != 'absolute') {
      st.style.position = 'absolute';
      st.style.top = topPos + 'px';
      updatedPos = 'absolute';
    } else if (pos >= topPos && updatedPos != 'fixed') {
      st.style.position = 'fixed';
      st.style.top = '0';
      updatedPos = 'fixed';
    }
  }
}
navPos(); //Thanks shinjuo and Adam Lynch!