/***************************/
/*        1. Header        */
/***************************/
header{
    background: url(../imgs/about_banner_bg.png) center center / cover no-repeat;
}
header .txt_box{
	padding: 16rem 0 14rem;
	display: flex;
	flex-direction: column;
	justify-content: center;
	align-items: center;
	color: #fff;
	font-weight: bolder;
}
header .txt_box>h1{
	font-size: 2.25rem;
	line-height: 2.25rem;
	font-weight: bolder;
}
header .txt_box>.des{
	font-size: 3rem;
	line-height: 3rem;
	font-weight: bolder;
	margin: 2rem 0 3rem;
}
header .txt_box>.line{
	width: 10rem;
	height: 3px;
	background-color: #fff;
}
/***************************/
/*           2.s1          */
/***************************/
.s1{
	border-bottom: 1px solid #eee;
}
.s1 .about_list{
	display: flex;
	justify-content: center;
	align-items: center;
}
.s1 .about_list>a{
	text-decoration: none;
	cursor: pointer;
	flex: 1;
	display: inline-flex;
	justify-content: center;
	align-items: center;
}
.s1 .about_list>a>span{
	display: inline-block;
	padding: 20px;
	text-align: center;
	font-size: 18px;
	line-height: 18px;
	color: #000;
	border-bottom: 2px solid transparent;
}
.s1 .about_list>a:focus>span{
	color: #004bdf;
	box-sizing: border-box;
	border-bottom: 2px solid #004bdf;
}
/***************************/
/*           2.s2          */
/***************************/
.s2 .tit{
	font-size: 2.25rem;
	line-height: 2.25rem;
	margin: 4rem 0 2rem;
	text-align: center;
}
.s2 .con_box{
	display: flex;
}
.s2 .con_box>.rt{
	padding: 0 20px;
}
.s2 .con_box>.rt .sub_tit{
	font-size: 1.5rem;
	line-height: 60px;
	color: #333333;
}
.s2 .con_box>.rt .sub_des{
	font-size: 16px;
	line-height: 24px;
	color: #666666;
}
.s2 .con_box>.rt>div:nth-child(1){
	height: 9.25rem;
}
.s2 .con_box>.rt>div:nth-child(2){
	height: 12.25rem;
}
.s2 .con_box>.rt>div:nth-child(3){
	height: 10.5rem;
}
/***************************/
/*           2.s3          */
/***************************/
.s3{
	padding: 5rem 0 10rem;
	background-color: #e0eaff;
	text-align: center;
}
.s3 .tit{
	font-size: 2.25rem;
	line-height: 2.25rem;
	font-weight: bold;
}
.s3 .des{
	font-size: 1.5rem;
	line-height: 1.5rem;
	margin: 1.5rem 0 4rem;
}
.s3 ul{
	display: flex;
	justify-content: space-around;
	align-items: center;
}
.s3 ul>li{
	flex: 1;
	display: flex;
	flex-direction: column;
	justify-content: center;
	align-items: center;
	padding: 4rem 0 3rem;
	margin: 0 10px;
	background-color: #fff;
	border-radius: 15px;
	box-shadow: 0px 0px 10px #9e9e9e;
	font-size: 1.5rem;
	line-height: 1.5rem;
	color: #666666;
}
.s3 ul>li>img{
	margin-bottom: 30px;
}
/**************************/
/*          4. s4         */
/**************************/
.s4{
    background: url(../imgs/khgl_useage_bg.jpg) center center / cover no-repeat;
}
.s4 .content{
	margin: 4.5rem 0 5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    color: #fff;
}
.s4 .content>.sub_tit{
    font-size: 1.5rem;
    line-height: 1.5rem;
    margin: 1.5rem 0 2rem;
}
.s4 .btn_box{
    margin-top: 2rem;
    display: flex;
}
.s4 .btn_box > a{
    display: block;
    cursor: pointer;
    text-align: center;
    width: 10rem;
    height: 3rem;
    font-size: 1rem;
    line-height: 3rem;
    font-weight: bold;
    /*border: 1px solid #fff;*/
    border-radius: 10px;
    box-sizing: border-box;
    margin-right: 2rem;
}
.s4 .btn_box>a:nth-child(1){
    background-color: #fff;
    color: #0f49ad;
}
.s4 .btn_box>a:nth-child(2){
    border: 1px solid #fff;
    color: #fff;
}
/**************************/
/*        5. media        */
/**************************/
@media (max-width: 768px){
	header .txt_box>h1{
		font-size: 1.875rem;
		line-height: 1.875rem;
	}
	header .txt_box>.des{
		font-size: 2.25rem;
		line-height: 2.25rem;
	}
	.s2 .tit{
		font-size: 1.875rem;
		line-height: 1.875rem;
	}
	.s3 .tit{
		font-size: 1.875rem;
		line-height: 1.875rem;
	}
	.s3 ul{
		display: flex;
		justify-content: space-around;
		align-items: center;
		flex-wrap: wrap;
	}
	.s3 ul>li{
		width: 50%;
		flex: none;
		margin: 0;
		border-radius: 0;
		box-shadow: none;
		border: 1px solid #eee;
		min-height: 222px;
	}
	.s3 ul>li:last-child{
		width: 100%;
	}
}
@media (max-width: 540px){
	html{
		font-size: 8px;
	}
	header .txt_box>h1{
		font-size: 2.5rem;
		line-height: 2.5rem;
	}
	header .txt_box>.des{
		font-size: 3rem;
		line-height: 3rem;
	}
	.s2 .tit{
		font-size: 3.75rem;
		line-height: 3.75rem;
		margin: 4rem 0 2rem;
		text-align: center;
	}
	.s2 .con_box>.rt .sub_tit{
		font-size: 2.5rem;
	}
	.s2 .con_box>.rt .sub_des{
		font-size: 14px;
		line-height: 20px;
	}
	.s2 .con_box>.rt>div:nth-child(1){
		height: 18.5rem;
	}
	.s2 .con_box>.rt>div:nth-child(2){
		height: 25rem;
	}
	.s2 .con_box>.rt>div:nth-child(3){
		height: 26.5rem;
	}
	.s3 .tit{
		font-size: 3rem;
		line-height: 3rem;
	}
	.s3 .des{
		font-size: 2.5rem;
		line-height: 2.5rem;
		margin: 3rem 0 8rem;
	}
	.s3 ul>li{
		font-size: 2.5rem;
		line-height: 2.5rem;
		min-height: 20rem;
	}
	/* useage */
    .s4 .content .sub_tit{
        font-size: 3rem;
        line-height: 3rem;
    }
    .s4 .btn_box > a{
	    width: 15rem;
	    height: 5rem;
	    font-size: 2rem;
	    line-height: 5rem;
	    margin: 0 4rem;
	}
}
@media (max-width: 414px){
	.s1 .about_list>a>span{
		padding: 20px 0;
		font-size: 16px;
		line-height: 16px;
	}
	.s2 .con_box>.rt>div{
		margin: 10px 0;
	}
	.s2 .con_box>.rt>div:nth-child(1), .s2 .con_box>.rt>div:nth-child(2), .s2 .con_box>.rt>div:nth-child(3){
		height: auto;
	}
}