transform-style

.demo_box{
    background:none;width:700px;height:300px;border:none;
}
.perspective{
    position:relative;width:200px;height:200px;float:left;margin:20px;
    -webkit-transform:perspective(300px);
    -moz-transform:perspective(300px);
}
.m3d{
    -moz-transform-style:preserve-3d;
    -webkit-transform-style:preserve-3d;
}
.perspective span{
    display:block;position:absolute;width:198px;height:198px;font-size:120px;line-height:198px;text-align:center;
    background:rgba(0,0,0,0.2);border:1px solid #333;
    
}
.front{
    -webkit-transform:rotateY(0deg) translateZ(100px);
    -moz-transform:rotateY(0deg) translateZ(100px);
}
.back{
    -webkit-transform:rotateY(180deg) translateZ(100px);
    -moz-transform:rotateY(180deg) translateZ(100px);
}
.right{
    -webkit-transform:rotateY(90deg) translateZ(100px);
    -moz-transform:rotateY(90deg) translateZ(100px);
}
.left{
    -webkit-transform:rotateY(-90deg) translateZ(100px);
    -moz-transform:rotateY(-90deg) translateZ(100px);
}
.top{
    -webkit-transform:rotateX(90deg) translateZ(100px);
    -moz-transform:rotateX(90deg) translateZ(100px);
}
.bottom{
    -webkit-transform:rotateX(-90deg) translateZ(100px);
    -moz-transform:rotateX(-90deg) translateZ(100px);
}
                   
                        

<div class="demo_box">
    <div class="perspective">
        <span class="front">1</span>
        <span class="back">2</span>
        <span class="right">3</span>
        <span class="left">4</span>
        <span class="top">5</span>
        <span class="bottom">6</span>
    </div>
    <div class="perspective m3d">
        <span class="front">1</span>
        <span class="back">2</span>
        <span class="right">3</span>
        <span class="left">4</span>
        <span class="top">5</span>
        <span class="bottom">6</span>
    </div>
</div>