:after擬似要素要素要素要素の後に内容を追加する
h2:after {width: 50px;height: 2px;display: block;content: "";background-color: #2FC1AC;margin-top: 20px; position: absolute; left: 50%; transform: translateX(-50%);}h2:after {width: 50px;height: 2px;display: block;content: "";background-color: #2FC1AC;margin-top: 20px; position: absolute; left: 50%; transform: translateX(-50%);}