css 实现矩形四个边角加粗

1、工具/原料

• html
• css

2、具体实现

效果图

• html代码

    
css实现矩形边角加粗
    

        
        
        
        
    

• css代码

        body{
            display: flex;
            justify-content: center;
            flex-direction: column;
            align-items: center;
        }
        .main{
            position: relative;
            width: 400px;
            height: 200px;
            border: 1px solid red;
        }
        .main span:nth-child(1){
            position: absolute;
            left: -5px;
            top: -5px;
            padding: 15px;
            border-style: solid;
            border-color: rebeccapurple;
            border-width: 5px 0 0 5px;
        }
        .main span:nth-child(2){
            position: absolute;
            right: -5px;
            top: -5px;
            padding: 15px;
            border-style: solid;
            border-color: rebeccapurple;
            border-width: 5px 5px 0 0;
        }
        .main span:nth-child(3){
            position: absolute;
            right: -5px;
            bottom: -5px;
            padding: 15px;
            border-style: solid;
            border-color: rebeccapurple;
            border-width: 0 5px 5px 0;
        }
        .main span:nth-child(4){
            position: absolute;
            left: -5px;
            bottom: -5px;
            padding: 15px;
            border-style: solid;
            border-color: rebeccapurple;
            border-width: 0 0 5px 5px;
        }

原理很简单， 只要弄清position:relative,border和left,top之间的关系就可以了