image.png
    可以通过 box-shadow 来实现边框的层叠效果
    box-shadow可以添加任意多个，所以只需要往四个边添加不同长度的 box-shadow 就能实现层叠效果

    1. > section {
    2.     border: 1px solid #05caec;
    3.     border-radius: 4px;
    4.     position: relative;
    5.     box-shadow: 0 0 2px 0 #0e4f5f, inset 0 0 2px 0 #0e4f5f;
    6.     background: #052831;
    8.   &::before {
    9.     content: '';
    10.     position: absolute;
    11.     left: 0;
    12.     right: 0;
    13.     bottom: 0;
    14.     top: 0;
    15.     border-radius: 4px;
    16.     box-shadow: 17px 0 0 -16px #0e4f5f, 
    17.       -17px 0 0 -16px #0e4f5f,
    18.       0 17px 0 -16px #0e4f5f, 
    19.       0 -17px 0 -16px #0e4f5f, 
    20.       9px 0 0 -8px #107881,
    21.       -9px 0 0 -8px #107881, 
    22.       0 9px 0 -8px #107881, 
    23.       0 -9px 0 -8px #107881;
    24.   }
    25. }