h1 {
  background: linear-gradient(transparent 50%, #a7d6ff 70%);
  font-size: 24px ;
}

a{
  text-decoration: none;
  font-size: 24px ;
  position: relative;
  display: inline-block;
  color: #616161 ;
  transition: .3s;
}

a::after {
  position: absolute;
  bottom: 0;
  left: 50%;
  content: '';
  width: 0;
  height: 4px;
  background-color: #448800;
  transition: .3s;
  transform: translateX(-50%);
}

a:hover::after{
  width: 100%;
}

.ribbon {
  display: inline-block;
  position: relative;
  height: 40px;/*高さ*/
  line-height: 40px;/*高さ*/
  text-align: center;
  padding: 0 40px 0 18px;/*文字の左右の余白*/
  font-size: 18px;/*文字サイズ*/
  background: #a7d6ff;/*背景色*/
  color: #000000;/*文字色*/
  box-sizing: border-box;
}

.ribbon:after {
  position: absolute;
  content: '';
  width: 0px;
  height: 0px;
  z-index: 1;
}

.ribbon:after {
  top: 0;
  right: 0;
  border-width: 20px 15px 20px 0px;
  border-color: transparent #fff transparent transparent;
  border-style: solid;
}