[Css] css は四隅の境界線を実現します。

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1. 効果:

2.実現：

background:
          linear-gradient(to top, #26aad1, #26aad1) left top no-repeat, //上左
          linear-gradient(to right, #26aad1, #26aad1) left top no-repeat, //左上
          linear-gradient(to left, #26aad1, #26aad1) right top no-repeat, //上右
          linear-gradient(to bottom, #26aad1, #26aad1) right top no-repeat, //上右
          linear-gradient(to left, #26aad1, #26aad1) left bottom no-repeat, //下左
          linear-gradient(to bottom, #26aad1, #26aad1) left bottom no-repeat, //左下
          linear-gradient(to top, #26aad1, #26aad1) right bottom no-repeat, //下右
          linear-gradient(to left, #26aad1, #26aad1) right bottom no-repeat; //右下
background-size: 2px 10px, 10px 2px, 2px 10px, 10px 2px;