body, ul, li, p {
    padding: 0;
    margin: 0;
}

body {
    padding: 100px 0;
    background: #ccc;
    font-family: Arial;
    color: #333;
}

p {
    line-height: 1.5em;
    margin-bottom: 1em;
}

#tabs {
    width: 400px;
    margin: auto;
}

#tabs > ul {
    list-style-type: none;
    overflow: hidden;
}

#tabs > ul > li {
    float: left;
}

#tabs > ul > li > a {
    display: block;
    height: 30px;
    line-height: 30px;
    margin-right: 2px;
    background: #A2A2A2;
    color: #CECECE;
    text-decoration: none;
    padding: 0 15px;
    border-top-left-radius: 3px;
    border-top-right-radius: 3px;
}

#tabs > div {
    display: none;
    padding: 15px;
    background: #EAEAEA;
    transition: opacity 200ms linear;
}

#tabs > div.visible {
    display: block;
}

#tabs > ul > li:first-of-type a {
    color: #333;
    background: #EAEAEA;
}

#tabs > div:first-of-type {
    display: block;
}