#portfolio {
    width: 100%;
    max-width: 600px;
    margin: 2em auto;
}

#portfolio-sort {
    text-align: center;
    padding-bottom: 3px;
    border-bottom: 1px solid #999;
    margin-bottom: 1em;
}

#portfolio-sort a {
    color: #fff;
    background: #a00;
    display: inline-block;
    padding: 3px 9px;
    text-decoration: none;
    margin-right: 1em;
}

#portfolio-content {
    overflow: hidden;
}

div.portfolio-item {
    float: left;
    margin: 0 3% 1em 0;
    width: 29%;
    height: 10em;
    line-height: 10;
    text-align: center;
}

div[data-cat="a"] {
    background: #ccc;
}

div[data-cat="b"] {
    background: #666;
    color: #fff;
}

div[data-cat="c"] {
    background: #333;
    color: #fff;
}