CSS 画三角形和正方体

1. 画三角形

三角形原理：边框的均分原理

设置 div 高为 0，四边设置边框宽度为 100px；

div {
    width: 0px;
    height: 0px;
    border-top: 100px solid red;
    border-right: 100px solid blue;
    border-bottom: 100px solid green;
    border-left: 100px solid transparent;
}

2. 画正方体

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>perspective</title>
    <style>
        .wrapper{
            width: 50%;
            float: left;
        }
        .cube{
            font-size: 4em;
            width: 2em;
            margin: 1.5em auto;
            transform-style: preserve-3d;
            transform: rotateX(-35deg) rotateY(30deg);
        }
        .side{
            position: absolute;
            width: 2em;
            height: 2em;
            background: rgba(255,99,71,0.6);
            border: 1px solid rgba(0,0,0,0.5);
            color: white;
            text-align: center;
            line-height: 2em;
        }
        .front{
            transform: translateZ(1em);
        }
        .bottom{
            transform: rotateX(-90deg) translateZ(1em);
        }
        .top{
            transform: rotateX(90deg) translateZ(1em);
        }
        .left{
            transform: rotateY(-90deg) translateZ(1em);
        }
        .right{
            transform: rotateY(90deg) translateZ(1em);
        }
        .back{
            transform: translateZ(-1em);
        }
    </style>
</head>
<body>
    <div class="wrapper w1">
        <div class="cube">
            <div class="side front">1</div>
            <div class="side back">6</div>
            <div class="side right">4</div>
            <div class="side left">3</div>
            <div class="side top">5</div>
            <div class="side bottom">2</div>
        </div>
    </div>
</body>
</html>