问题 求问，这个图标是如何输出的

[class^="tm-icon-yootheme-"], [class*=" tm-icon-yootheme-"] {
  font-family: "yootheme";
  font-size: 72px;
  font-style: normal;
  font-variant-alternates: normal;
  font-variant-caps: normal;
  font-variant-east-asian: normal;
  font-variant-ligatures: normal;
  font-variant-numeric: normal;
  font-variant-position: normal;
  font-weight: normal;
  line-height: 1;
  text-transform: none;
}