小库网 

<style>

ul {

    list-style-type: none;

}

​

ul li a {

    color: green;

    text-decoration: none;

    padding: 3px; 

    display: block;

}

​

@media screen and (max-width: 699px) and (min-width: 520px) {

    ul li a {

        padding-left: 30px;

        background: url(email-icon.png) left center no-repeat;

    }

}