CSS3:ドッグイヤ
code:css
.corner_box {
background: rgba(247, 17, 55, 0.8);
width: 200px;
height: 230px;
position: relative;
}
.corner_box:before {
height: 0;
display: block;
position: absolute;
right: 0;
content: "";
border-top: solid 50px #fff;
border-left: solid 50px transparent;
}
.corner_box:after {
height: 0;
display: block;
position: absolute;
right: 0;
content: "";
border-bottom: solid 50px rgba(28, 24, 196, 0.8);
border-right: solid 50px transparent;
top: 0;
}
dog ear ; dogeared
ドッグイヤ、犬の耳
ドッグイヤー（dog year）
ブックマーク
しおり
角折れ
CSS3:ボーダー
CSS3:擬似要素
#CSS3-tips
https://img.shields.io/badge/CSS3-ドッグイヤ-1572B6.svg?logo=css3&style=for-the-badge