h2 {
  position: relative;
  height: 50px;  /*リボンの高さ*/
  line-height: 50px;  /*文字の位置*/
  padding: 0 40px;  /*文字の開始位置*/
  color: #ffffff;  /*文字色*/
  font-size: 25px;  /*文字サイズ*/
  background-color: #e53939;  /*背景色*/
}
h2::before,
h2::after {
  position: absolute;
  content: '';
  width: 0px;
  height: 0px;
  z-index: 1;
}
h2::before {
  top: 0;
  left: 0;
  top: 0;
  left: -25px;
  border-width: 25px;
  border-right-color: #e53939;
  border-style: solid;
  border-style: solid;
}
h2::after {
  top: 0;
  right: 0;
  border-width: 25px 25px 25px 25px;
  border-style: solid;
  border-color: transparent #ffffff transparent transparent;
  border-right-color: #ffffff;
}