<div class="container">
<a href="#" class="btn-animation-02"><span>PUSH ME<span></a>
</div>
/* ここはコピーしなくてOK */
.container {
  font-family: "Yu Gothic", YuGothic, Verdana, 'Hiragino Kaku Gothic ProN','Hiragino Kaku Gothic Pro', 'ヒラギノ角ゴ Pro W3', 'メイリオ', Meiryo, sans-serif;
  text-align: center;
  padding-top: 40px;
}


/* ここから下がボタンのCSS */
.btn-animation-02 {
  display: inline-block;
  width: 200px;
  text-align: center;
  background-color: #9ec34b;
  border: 2px solid #9ec34b;
  font-size: 16px;
  color: #9ec34b;
  text-decoration: none;
  font-weight: bold;
  padding: 10px 24px;
  border-radius: 4px;
  position: relative;
}

.btn-animation-02 span {
  position: relative;
  z-index: 1;
}

.btn-animation-02::before,
.btn-animation-02::after {
  content: "";
  display: block;
  background-color: #FFF;
  width: 50%;
  height: 100%;
  position: absolute;
  top: 0;
  transition: .2s;
}
.btn-animation-02::before {
  left: 0;
}
.btn-animation-02::after {
  right: 0;
}

.btn-animation-02:hover:before,
.btn-animation-02:hover:after {
  width: 0;
  background-color: #FFF;
}

.btn-animation-02:hover {
  color: #FFF;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.