before和after伪元素问题

before和after的两个四色块不应该是一个在前面一个在后面吗，效果怎么不是呢？还有一个问题是before和after设置的border应该是正方型的 这个怎么显示是长方形

img

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .one{
            /* height: 200px; */
            /* width: 200px; */
            width: 0px;
            height: 0px;
            /* background-color: aquamarine; */
            margin-top: 100px;
            border: 50px solid red;
            /* border-top-width: 0px ; */
            /* border-color: red blue green yellow; */
            /* border-color: transparent transparent green transparent; */
        }
        .one::before{
            content: "";
            border: 50px solid red;
            border-color: red blue green yellow;
        }
        .one::after{
            content: "";
            border: 50px solid red;
            /* margin-top: 100px; */
            /* margin-left: 100px; */
            width: 0px;
            height: 0px;
            /* border-color: blue transparent transparent transparent; */
            border-color: red blue green yellow;
        }
        .two{
            height: 100px;
            width: 100px;
            background-color: brown;
        }
    </style>
</head>
<body>
    <div class="one"></div>
    <!-- <div class="two"></div> -->
</body>
</html>
```和发生背景

:before 没给宽高