style.css

body{
    margin:0;
    padding:0;
    font-size:12px;
    background: #2980b9
    url('images/bg.png') repeat 0 0;
    background-size: auto 100%;
    -webkit-animation: 10s linear 0s normal none infinite animate;
    -moz-animation: 10s linear 0s normal none infinite animate;
    -ms-animation: 10s linear 0s normal none infinite animate;
    -o-animation: 10s linear 0s normal none infinite animate;
    animation: 10s linear 0s normal none infinite animate;
    }

    html {
        font-family: 'Ubuntu', sans-serif;
        font-weight: 400;
        font-size: 14px;
        color: white;
    }

    .container {
        max-width: 400px;
        margin: 2em auto;
        text-align: center;
        line-height: 1.5;
    }

    h1 {
        margin: 6em 1em auto;
    }

    a {
        text-decoration: none;
        color: rgb(255, 255, 255);
        font-weight: 700;
    }

    span.purple {
        color: purple;
        font-weight: 700;
    }

    span.black {
        color: black;
        font-weight: 700;
    }

    .tic-tac-toe {
        width: 315px;
        height: auto;
        margin: 0 auto;

    }

    .tile {
        height: 100px;
        width: 100px;
        display: inline-block;
        cursor: pointer;

        position: relative;
        vertical-align: top;

        padding: 15px;
        margin-bottom: 5px;
        box-sizing: border-box;

        color: #fff;
        font-size: 60px;
        text-align: center;
    }

    .free {
        background-color: #fff;
    }

    .O-play {
        background-color: black;
    }

    .X-play {
        background-color: purple;
    }

    @-webkit-keyframes animate {
    from {background-position:0 0;}
    to {background-position: 500px 0;}
    }
    @-moz-keyframes animate {
    from {background-position:0 0;}
    to {background-position: 500px 0;}
    }
    @-ms-keyframes animate {
    from {background-position:0 0;}
    to {background-position: 500px 0;}
    }
    @-o-keyframes animate {
    from {background-position:0 0;}
    to {background-position: 500px 0;}
    }
    @keyframes animate {
    from {background-position:0 0;}
    to {background-position: 500px 0;}
    }