擬似要素 (pseudo elements) 一覧 参考： Pseudo-elements – CSS: Cascading Style Sheets | MDN CSS Pseudo Element List | Mads Kristensen ネイティブ要素 参考： A CSS pseudo-element is used to style specified parts of an element. In some cases you can style native HTML controls with vendor specific pseudo-elements. Here you will find an list of cross browser specific pseudo-element selectors. – GitHub Gist タグ： CSS