CSS3 uses transform to create a moving 2D clock

<div id="clock-wrap">
	<div id="clock">
    	<ul id="list">
        </ul>
    </div>
    <div id="num">
    	<ul>
        	<li>12</li>
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
            <li>5</li>
            <li>6</li>
            <li>7</li>
            <li>8</li>
            <li>9</li>
            <li>10</li>
            <li>11</li>
        </ul>
    </div>
    <div id="hour"></div>
    <div id="min"></div>
    <div id="sec"></div>
    <div id="circle"></div>
</div>

<style id="css">/*Note that an id is added to the style tag, which is obtained in JavaScript and the css style is added to it. */
body,ul{
	margin:0;
	padding:0;}
body{
	font:1em "microsoft Yahei";
	color:#666;
	background-color:#333;}
h1{
	text-align:center;
	color:#eee;
	font-size:3rem;}
li{
	list-style:none;}
p{
	text-align:center;
	color:#ddd;
	position:relative;
	top:100px;
	}
a{
	color:#999;
	text-decoration:none;
	transition:0.2s;}
a:hover{
	color:#ddd;}
#clock-wrap{
	width:400px;
	height:400px;
	border:10px solid #fff;
	border-radius:50%;
	margin:80px auto 0;
	position:relative;
	box-shadow:0 0 40px rgba(0,0,0,1)}
#clock ul{
	width:400px;
	height:400px;
	position:relative;
	border-radius:50%;
	background:radial-gradient(circle at center,#667eea,#764ba2);
	box-shadow:0 0 50px rgba(0,0,0,0.5) inset; /*Set inner shadow*/
	}
#clock ul li{
	position:absolute;
	left:50%;
	margin-left:-2px;
	top:0;
	width:4px;
	height:10px;
	background:rgba(255,255,255,.5);
	transform-origin:center 200px; /*li's rotation center is in the middle of the circle. */
	}
#clock li:nth-child(5n+1){ /*5 scales form a group, and the first scale of each group should be longer. */
	height:18px;
	}
#num{
	position:absolute;
	width:360px;
	height:360px;
	left:0;
	right:0;
	top:0;
	bottom:0;
	margin:auto;
	}
#num li{
	position:absolute;
	left:50%;
	margin-left:-10px;
	top:0;
	color:rgba(255,255,255,.5);
	font:2em Arial, Helvetica, sans-serif;	
	transform-origin:center 180px;}

#hour,#min,#sec
	background:#fff;
	position:absolute;
	left:50%;
	top:50%;
	transform-origin:bottom; /*The rotation point of the hour hand is at its bottom. */
	box-shadow:0 0 6px rgba(0,0,0,.5)
	}
#hour{
	width:14px;
	height:100px;
	margin-left:-7px;
	margin-top:-100px;
	border-radius:3px;
	}
#min{
	width:10px;
	height:150px;
	margin-left:-5px;
	margin-top:-150px;
	border-radius:2px;
	}
#sec{
	width:4px;
	height:180px;
	margin-left:-2px;
	margin-top:-180px;
	border-radius:1px;
	}
#circle{
	width:40px;
	height:40px;
	border-radius:50%;
	background:#fff;
	position:absolute;
	left:50%;
	margin-left:-20px;
	top:50%;
	margin-top:-20px;
	box-shadow:0 0 20px rgba(0,0,0,.4)}
</style>

<script>
window.onload = function(){
	var oList = document.getElementById("list");
	var oCSS=document.getElementById("css"); //The style tag can also add an id attribute.
	var aNums = document.getElementById("num").getElementsByTagName("li");
	var oHour = document.getElementById("hour");
	var oMin = document.getElementById("min");
	var oSec=document.getElementById("sec");
	var aLi="";
	var sCSS="";
	for(var i=0;i<60;i++){ //Loop 60 times to generate the scale value and the degree of rotation of each scale.
		aLi+="<li></li>";
		sCSS+="#clock li:nth-child("+(i+1)+"){transform:rotate("+i*6+"deg);}"
		}
	for(var i=0;i<12;i++){
		sCSS+="#num li:nth-child("+(i+1)+"){transform:rotate("+i*30+"deg);}"
		}
	oList.innerHTML=aLi;
	oCSS.innerHTML+=sCSS; //css needs to be appended to the original css document.
	
	
	
	myTime(); //Initialization function.
	setInterval(myTime,1000); //Set the timer to execute the function every 1 second.
	function myTime(){
		var oDate=new Date();
		var iSec=oDate.getSeconds(); 
		//Minutes with precision to seconds.
		var iMin=oDate.getMinutes()+iSec/60; 
		//Hours accurate to minutes and seconds. Can be more precise when rotating.
		var iHour=oDate.getHours()+iMin/60;
		
		oSec.style.transform="rotate("+iSec*6+"deg)";
		oMin.style.transform="rotate("+iMin*6+"deg)";
		oHour.style.transform="rotate("+iHour*30+"deg)"; //The direction of the hour hand needs to include minutes and seconds to be accurate.
		}
	
	}
</script>