【css

<picture><source media="(max-width: 480px)" srcset="图片地址"><source media="(min-width: 481px)" srcset="图片地址"><img src="图片地址" id="homebanner"></picture>

img{height: 290px;width: 100%;
}
// 小于992px
@media (max-width: 992px) { img{width: 100%;height: 180px;}
}

【css

<picture><source media="(max-width: 480px)" srcset="图片地址"><source media="(min-width: 481px)" srcset="图片地址"><img src="图片地址" id="homebanner"></picture>

img{height: 290px;width: 100%;
}
// 小于992px
@media (max-width: 992px) { img{width: 100%;height: 180px;}
}