code: function(el, selectEl) {
                      var rect = selectEl.getBoundingClientRect();
                      var dropdownHeight = el.clientHeight;
                      var openUpwards =
                          rect.bottom + dropdownHeight > window.innerHeight &&
                          rect.top - dropdownHeight > 0;
  
                      assign(el.style, {
                          left: rect.left + 'px',
                          top: (openUpwards ? rect.top - dropdownHeight : rect.bottom) + 'px',
                          width: rect.width + 'px'
                      });
                  }
docs: dropdowns for multiple-value inputs should open below the select box, unless there is not enough space below, but there is space enough above, then it should open upwards