WebKit Animation

HTML

<div class="box a"></div>
<div class="box b"></div>

CSS

@-webkit-keyframes move {
    0%   { width: 10px;  }
    50%  { width: 200px; }
    100% { width: 10px;  }
}

.box {
    background: #222;
    margin: 10px;
    height: 50px;
    width: 200px;
}

.a {
    -webkit-animation: move 10s linear infinite;
    background: #95CDC6;
}

.b {
    -webkit-animation: move 10s linear 5s infinite;
    background: #AED66E;
}