Several fixes for Bootstrap 3 Modals when using forms and iOS

gistfile1.js

//Modals, several fixes      
      $('.modal').on('show.bs.modal', function() {
        $("#page input:not(:disabled), #page select:not(:disabled)").addClass('twerked').prop("disabled", true);
        
        var measureScrollBar = function () {
            var scrollDiv = document.createElement('div')
            scrollDiv.style = 'width: 1px;height: 1px;overflow: scroll;position: absolute;top: -9999px;'
            document.body.appendChild(scrollDiv)
            var scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth
            document.body.removeChild(scrollDiv)
            return scrollbarWidth
        }
          
        if( navigator.userAgent.match(/iPhone|iPad|iPod/i) ) {
          $(this).css({
            position: 'absolute',
            marginTop: $(window).scrollTop() + 'px',
            bottom: 'auto'
          });

          setTimeout( function() {
            $('.modal-backdrop').css({
              position: 'absolute', 
              top: 0, 
              left: 0,
              width: '100%',
              height: $(document).height() + 'px'
            });
          }, 0);
        }
        
        if (this.clientHeight <= window.innerHeight) return
        var scrollbarWidth = measureScrollBar()
        if (scrollbarWidth) $(document.body).css('padding-right', scrollbarWidth)
      }).on('hidden.bs.modal', function () {
        $("#page .twerked").removeClass('twerked').prop("disabled", false);
        $(document.body).css('padding-right', 0)
      });