tryresponsive_image_picture 在线代码实例

 <picture>
    <source srcset="/statics/images/course/img_smallflower.jpg" media="(max-width: 400px)">
    <source srcset="/statics/images/course/img_flowers.jpg">
    <img src="/upload2/statics/images/course/img_flowers.jpg" alt="Flowers" style="width:auto;">
</picture>

<p>调整浏览器宽度和高度，背景在宽度小于 400px 时将改变。 </p>