animation-delay

.demo_box{
    -webkit-animation:f1 2s  forwards ease;
    -moz-animation:f1 2s  forwards ease;
    position:relative;
    left:10px;
    width:100px;
    height:100px;
    margin:10px 0;
    overflow:hidden;
}
.no_delay{ 
    -webkit-animation-delay:0;
    -moz-animation-delay:0;
}
.delay_2s{
    -webkit-animation-delay:2s;
    -moz-animation-delay:2s;
}
.delay_-1s{
    -webkit-animation-delay:-1s;
    -moz-animation-delay:-1s;
}

@-webkit-keyframes f1{
    0%{left:10px;}
    100%{left:500px;}
}
@-moz-keyframes f1{
    0%{left:10px;}
    100%{left:500px;}
}                        
                        

<div class="demo_box no_delay">动画立即执行</div>
<div class="demo_box delay_2s">动画延迟2秒执行</div>
<div class="demo_box delay_-1s">动画前一秒被截断</div>