* {
	margin: 0;
	padding: 0;
}

body {
	background: url(https://pic.imgdb.cn/item/655b1ac0c458853aef64cf2d.jpg);
}
.nav {
    width: 600px;    /* 导航条居中宽度要与导航条长度一致 */
    margin: 0 auto;
}
.nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}
.nav li {
    float:left; 
    /* display: inline; */
    background-color: #00bbcc3c;
    width:100px;
    height:30px;
    text-align: center;
}
.nav a {
    font-size: 14px;
    color: rgb(61, 61, 61);
    font-weight: bold;
    text-decoration: none;
    line-height: 30px;
    display: block;
}
.nav li a:hover {
    background-color: #00cc99;
}
.nav li ul {
    display: none;
}
.nav li:hover ul{
    display: block;
}
.pd {
	width: 300px;
	height: 300px;
	position: absolute;
	top: 0;
	bottom: 0;
	left: 0;
	right: 0;
	margin: auto;
	/*3d空间*/
	transform-style: preserve-3d;
	animation: box 20s linear infinite;
}

@keyframes box {

	/*3d旋转 x y z deg*/
	from {
		transform: rotate3d(0, 0, 0, 0deg);
	}

	to {
		transform: rotate3d(1, 1, 1, 360deg);
	}
}

.pd li {
	width: 300px;
	height: 300px;
	list-style: none;
	border: 1px solid black;
	position: absolute;
	opacity: 0.8;
	box-shadow: 0px 0px 10px white;
}

.pd li:nth-child(1) {
	background: url(https://pic.imgdb.cn/item/655b1abac458853aef64bdf6.jpg);
	background-position: center;
	background-size: cover;
	transform: translateZ(150px);
}

/*后*/
.pd li:nth-child(2) {
	background: url(https://pic.imgdb.cn/item/655b1a90c458853aef6443f4.jpg);
	background-position: center;
	background-size: cover;
	transform: translateZ(-150px);
}

/*左*/
.pd li:nth-child(3) {
	background: url(https://pic.imgdb.cn/item/655b1a85c458853aef6420dd.jpg);
	background-position: center;
	background-size: cover;
	transform: rotateY(90deg) translateZ(-150px);
}

/*右*/
.pd li:nth-child(4) {
	background: url(https://pic.imgdb.cn/item/65579336c458853aefaa3e8e.jpg);
	background-position: center;
	background-size: cover;
	transform: rotateY(90deg) translateZ(150px);
}

/*上*/
.pd li:nth-child(5) {
	background: url(https://pic.imgdb.cn/item/654b9c11c458853aefa8cc96.jpg);
	background-position: center;
	background-size: cover;
	transform: rotateX(90deg) translateZ(150px);
}

.pd li:nth-child(6) {
	background: url(https://pic.imgdb.cn/item/65446059c458853aef07cf65.png);
	background-position: center;
	background-size: cover;
	transform: rotateX(90deg) translateZ(-150px);
}

.pd:hover {
	animation-play-state: paused;
}