content: "\e600"

w图标生成原理。

 <style>
     @font-face {
         font-family: iconfont-sm;
         src: url(//at.alicdn.com/t/font_1433401008_2229297.woff) format('woff'), url(//at.alicdn.com/t/font_1433401008_2229297.ttf) format('truetype'), url(//at.alicdn.com/t/font_1433401008_2229297.svg#iconfont) format('svg')
     }

     .icon {
         font-family: iconfont-sm !important;
         font-style: normal;
         display: inline-block;
         vertical-align: middle;
         background-size: 100% auto;
         background-position: center;
         -webkit-font-smoothing: antialiased;
         -webkit-text-stroke-width: .2px;
         -moz-osx-font-smoothing: grayscale
     }

     .icon-cart:before {
         content: "\e600"
     }
 </style>

 <P class=" icon icon-cart">This is a somewhat long HTML
     paragraph   </P>