.since2021 {
  /* display: none; */
  color: blue;
}

.since2021::after {
  content: "新";
  vertical-align: super;
  font-size: 71%;
}

.till2020 {
  color: red;
}

.till2020::after {
 content: "旧";
 vertical-align: super;
 font-size: 71%;
}