//导航菜单
  layui.use(['jquery', 'element', 'carousel'], function(){
      var $ = layui.jquery
      ,element = layui.element
      ,carousel = layui.carousel
    
      //滚动监听
      $(window).scroll(function() {
        var scr=$(document).scrollTop();
        scr > 0 ? $(".nav").addClass('scroll') : $(".nav").removeClass('scroll');
      });

    //导航切换
      var btn = $('.nav').find('.nav-list').children('button')
      ,spa = btn.children('span')
      ,ul = $('.nav').find('.nav-list').children('.layui-nav');
      btn.on('click', function(){
        if(!$(spa[0]).hasClass('spa1')){
          spa[0].className = 'spa1';
          spa[1].style.display = 'none';
          spa[2].className = 'spa3';
          $('.nav')[0].style.height = 90 + ul[0].offsetHeight + 'px';
        }else{
          spa[0].className = '';
          spa[1].style.display = 'block';
          spa[2].className = '';
          $('.nav')[0].style.height = 60 + 'px';
        }
      });
  });

//返回顶部
window.onscroll = function() {scrollFunction()};
function scrollFunction() {
    if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
        document.getElementById("gotop").style.display = "block";
    } else {
        document.getElementById("gotop").style.display = "none";
    }
}
function topFunction() {
    document.body.scrollTop = 0;
    document.documentElement.scrollTop = 0;
}