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CSS

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <div class="btn-rot">
  <a href="#">周るように光るボタン</a>
</div>
!

CSS 

              
                /*** ボタンブロック ***/
.btn-rot{
  text-align: center;
  margin: 2rem;
  overflow: hidden; /*必須*/
}

/* ボタン（リンク）部分 */
.btn-rot a{
  text-decoration: none; /*下線削除*/
  display: inline-block;
  position: relative; /*疑似要素作成用*/
  padding: 0.75em 4em;
  margin: 1rem;
  background: white; /*ボタン色*/
  color: green; /*文字色*/
  font-weight: bold; /*太字*/
}

/*ボタンの枠線*/
.btn-rot a:before{
  content: "";
  position: absolute;
  top: -3px;
  left: -3px;
  width: 100%;
  height: 100%;
  border: 3px solid green;
  z-index: -2;
}

/*** ボタン線上の光沢 ***/
.btn-rot a:after{
  content: "";
  position: absolute;
  top: -30px;
  left: -100px;
  width: 100px;
  height: 30px;
  background: white; /*光沢の色は背景色*/
  filter: blur(12px); /*ぼかし*/
  animation: 3s arround-circle linear infinite; /*枠線場を周るアニメーション*/
  z-index: -1;
}

/*** 線上を回るアニメーション ***/
@keyframes arround-circle{
  /**************
  0%~40%：左上から右上
  40%~50%：右上から右下
  50%~90%：右下から左下
  90%~100%：左下から左上
  **************/
  0%{
    top: -30px;
    left: -100px;
  }
  40%{
    top: -30px;
    left: 100%;/*右まで移動*/
  }
  50%{
    top: 100%; /*下まで移動*/
    left: 100%;
  }
  90%{
    top: 100%;
    left: -100px; /*左まで移動*/
  }
  100%{
    top: -30px; /*元の位置*/
    left: -100px;
  }
}
!

JS
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999px

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