.blog {
    background: url(../img/rss-black.png) no-repeat;
    background-size: auto 15px;
}

.blog:hover, .blog:focus {
    background: url(../img/rss-gray.png) no-repeat;
    background-size: auto 15px;
}

.centrado-porcentual {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    -webkit-transform: translate(-50%, -50%);
}

ul li {
    padding: 2px 0px;
    width: 120px;
    padding-right: 10px;
}