JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">로그인</div>
<div class="box">고객센터</div>

CSS

.box {
  position: relative;
  color: #fff;
  padding: 5px 10px;
  display: inline-block;
}
.box:before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: -1;
  background: #666;
  transform: skew(10deg);
}