实现宽高等比例自适应矩形
.scale {
width: 100%;
padding-bottom: 56.25%;
height: 0;
position: relative;
}
.item {
position: absolute;
width: 100%;
height: 100%;
background-color: 499e56;
} 
.scale {
width: 100%;
padding-bottom: 56.25%;
height: 0;
position: relative;
}
.item {
position: absolute;
width: 100%;
height: 100%;
background-color: 499e56;
}