.main-content{
	background: #fff;
	margin-top: 30px;
	color: #000000;
	width: 90%;
	margin-left: 5%;
}

.introduc-title {
	border-bottom: 2px solid #00a0e9;
    width: 100px;
    text-align: center;
    margin-left: 10px;
    margin-top: 5px;
     color: #e60012;
} 
.introduc{
	margin:10px;
	width:90%;
}
.main-class{	
   margin-top: 70px;
   min-height: calc(100vh - 170px);
   margin-bottom: -50px;
   position: absolute;
 }
 @media screen and (max-width: 991px) { /*当屏幕尺寸小于991px时，应用下面的CSS样式*/
  .main-class {
    min-height:800px;
    margin-top: 55px;
	margin-bottom: -50px;
	position: absolute;
  }     
 }

@media (max-width: 991px){
  .footer{
    height: 40px;
  }
}

@media screen and (max-width: 1021px) {
  .introduc-title{
  	 width: 80px;
  	  color: #e60012;
  }
}
.image-item{
	height: 500px;
	width: 100%;
	margin-left:0%;
}

.font-sty{
	letter-spacing: 3px;
    font-size: 20px;
    font-weight:600;
    
}
@media (max-width: 991px){
    .image-item{
      width: 100%;
      height: 100%;
      margin-left: 0px;
    }
  }
.main-footer {
    background: #00a0e9;
    color: #fff;
    position: absolute;
	width: 100%;
	text-align:center;
	height: 50px;
	clear: both;
    display: block;
    vertical-align:middle;
}

.header .nav .sub .level1 {
  background: #00a0e9;
}