フチだけ残るアウトラインボタン（ホバーで塗りつぶし）

<div class="push-button_box">
  <a href="#" class="push-button outline-hover">詳細をチェック</a>
</div>

.push-button_box{
  width:30%;
  margin:50px auto;
}

.push-button.outline-hover {
  display: block;
  width: 100%;
  padding: 14px 0;
  background: transparent;
  border: 2px solid #3b82f6;
  color: #3b82f6;
  font-size: 16px;
  font-weight: bold;
  text-align: center;
  border-radius: 6px;
  text-decoration: none;
  transition: 0.3s ease;
}

.push-button.outline-hover:hover {
  background: #3b82f6;
  color: #fff;
}