@media screen and (max-width:768px){
   .m_box .m_left .m_line ul li dl{position:absolute;z-index: 9;background: #fff;left: 0;right: 0;top: 100%;z-index: 10;margin: 0;width: 100%;box-shadow: 0px 10px 10px rgba(0,0,0,.1); 
          display: none !important;}
          
          
          } 
   .m_box .m_left .m_line ul li dl{background: rgba(51,51,51,.05);margin: 0 15px 10px 15px;display: block;}