伪类+js实现CSS3 media queries跨界准确判断
@media screen and (min-width: 45em) { body:after{ content:"宽屏" } }
var content = window.getComputedStyle(document.body, ":after").getPropertyValue("content");if (content === "窄屏") {// ……
} else if (content === "普屏") {// ……
} else if (content === "宽屏") {// ……
}