border添加漸變色 border-radius無效問題

border添加漸變色，IOS上圓形是不支持的，可以通過設置padding之後添加背景色漸變實現

<img class="box" src="./default/face.png" />

      .box {
        display: block;
        width: 100px;
        height: 100px;
        border-radius: 50%;
        box-sizing: border-box;
        padding: 5px;
        background-image: -webkit-linear-gradient(
          top,
          red 0%,
          blue 30%,
          yellow 60%,
          green 90%
        );
        background-image: -moz-linear-gradient(
          top,
          red 0%,
          blue 30%,
          yellow 60%,
          green 90%
        );
        background-image: linear-gradient(
          top,
          red 0%,
          blue 30%,
          yellow 60%,
          green 90%
        );
      }