只用一個div實現一個八卦圖

效果圖：

html：

<div></div>

css:

<style>
        div{
            width: 100px;
            height: 200px;
            background: #fff;
            position: absolute;
            left: 0;
            right: 0;
            top:0;
            bottom: 0;
            margin: auto;
            border-style: solid;
            border-color: #000;
            border-width: 1px 100px 1px 1px;
            border-radius: 50%;
        }
        div:before {
            content: '';
            background: #000;
            width: 20px;
            height: 20px;
            border: 40px solid #fff;
            border-radius: 100%;
            position: absolute;
            left: 50%;
            top: 0;
        }
        div:after {
            content: '';
            background: #fff;
            width: 20px;
            height: 20px;
            border: 40px solid #000;
            border-radius: 100%;
            position: absolute;
            right: -50%;
            bottom: 0;
        }
    </style>
 

補：加一個小小的動畫

效果：讓八卦圖順時針旋轉
html程式碼：

<div></div>

css程式碼:

<style>
        div{
            width: 100px;
            height: 200px;
            background: #fff;
            position: absolute;
            left: 0;
            right: 0;
            top:0;
            bottom: 0;
            margin: auto;
            border-style: solid;
            border-color: #000;
            border-width: 1px 100px 1px 1px;
            border-radius: 50%;
            animation: change 3s;/*引數1：動畫名稱；引數2：規定動畫完成一個週期所花費的秒或毫秒。預設是 0。*/
            animation-iteration-count: infinite;/*設定動畫次數無限[預設值是1]*/
            animation-timing-function: linear;/*使動畫勻速旋轉[預設值是ease，動畫以低速開始，然後加快，在結束前變慢。]*/
        }
        div:before {
            content: '';
            background: #000;
            width: 20px;
            height: 20px;
            border: 40px solid #fff;
            border-radius: 100%;
            position: absolute;
            left: 50%;
            top: 0;
        }
        div:after {
            content: '';
            background: #fff;
            width: 20px;
            height: 20px;
            border: 40px solid #000;
            border-radius: 100%;
            position: absolute;
            right: -50%;
            bottom: 0;
        }
        /*@keyframes:規定動畫。*/
        @keyframes change {
            0% {transform: rotate(0deg)}
            100% {transform: rotate(360deg)}
        }
    </style>