基于CSS3技术，炫酷3D立方体预加载loading特效

<link rel="stylesheet" type="text/css" href="css/bootstrap-grid.min.css" />

<div class="demo" style="min-height:350px;">
<div class="container">
<div class="row">
<div class="col-md-12">
<div class="loader">
<div class="box">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>
<div class="box">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>
<div class="box">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>
<div class="box">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>
</div>
</div>
</div>
</div>
</div>

.loader{
                    --size: 32px;
                    --duration: 800ms;
                    width: 96px;
                    height: 64px;
                    margin: 50px auto;
                    transform-style: preserve-3d;
                    transform-origin: 50% 50%;
                    transform: rotateX(60deg) rotateZ(45deg) rotateY(0deg) translateZ(0px);
                    position: relative;
                }
                .loader .box{
                    width:  32px;
                    height: 32px;
                    transform-style: preserve-3d;
                    position: absolute;
                    top: 0;
                    left: 0;
                }
                .loader .box:nth-child(1){
                    transform: translate(100%, 0);
                    animation: box1 800ms linear infinite;
                }
                .loader .box:nth-child(2){
                    transform: translate(0, 100%);
                    animation: box2 800ms linear infinite;
                }
                .loader .box:nth-child(3){
                    transform: translate(100%, 100%);
                    animation: box3 800ms linear infinite;
                }
                .loader .box:nth-child(4){
                    transform: translate(200%, 0);
                    animation: box4 800ms linear infinite;
                }
                .loader .box > div{
                    --translateZ: calc(var(--size) / 2);
                    --rotateY: 0deg;
                    --rotateX: 0deg;
                    background: #5c8df6;
                    width: 100%;
                    height: 100%;
                    transform: rotateY(var(--rotateY)) rotateX(var(--rotateX)) translateZ(var(--translateZ));
                    position: absolute;
                    top: auto;
                    right: auto;
                    bottom: auto;
                    left: auto;
                }
                .loader .box > div:nth-child(1){
                    top: 0;
                    left: 0;
                }
                .loader .box > div:nth-child(2){
                    background: #145af2;
                    right: 0;
                    --rotateY: 90deg;
                }
                .loader .box > div:nth-child(3){
                    background: #447cf5;
                    --rotateX: -90deg;
                }
                .loader .box > div:nth-child(4){
                    background: #dbe3f4;
                    top: 0;
                    left: 0;
                    --translateZ: calc(var(--size) * 3 * -1);
                }
                @keyframes box1{
                    0%, 50%{ transform: translate(100%, 0); }
                    100%{ transform: translate(200%, 0); }
                }
                @keyframes box2{
                    0%{ transform: translate(0, 100%); }
                    50%{ transform: translate(0, 0); }
                    100%{ transform: translate(100%, 0); }
                }
                @keyframes box3{
                    0%, 50%{ transform: translate(100%, 100%); }
                    100%{ transform: translate(0, 100%); }
                }
                @keyframes box4{
                    0%{ transform: translate(200%, 0); }
                    50%{ transform: translate(200%, 100%); }
                    100%{ transform: translate(100%, 100%); }
                }