srcset属性配合w宽度描述符配合sizes属性

<div> 
    <p>srcset w 自动选择：</p>
    <img 
         sizes="(min- 600px) 600px, 300px"
         src="https://vmat.gtimg.com/kt/ktweb/pay/imgs/act/cql@1x.png"
         srcset="https://vmat.gtimg.com/kt/ktweb/pay/imgs/act/cql@1x.png 300w,
                 https://vmat.gtimg.com/kt/ktweb/pay/imgs/act/cql@2x.png 600w,
                 https://vmat.gtimg.com/kt/ktweb/pay/imgs/act/cql@3x.png 1200w"
         >
</div>

css

html,
body {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: space-around;
    padding: 0 20px;
    box-sizing: border-box;
}

p {
    font-size: 28px;
    line-height: 2;
    text-align: center;
}

img {
    display: block;
    width: 300px;
}

@media screen and (min- 600px) {
    img {
        width: 600px;
    }
}
div {
    margin: 0 auto;
}