crbtc.org/assets/style/pages/index/_hero.scss

.hero {
  padding: calc(50vh - 240px) 0 10vh 0;

  h3 {
    color: $f-color;
    font-size: 4rem;
    line-height: 4rem;
    text-align: center;

    span {
      position: relative;
      color: $btc;

      &:after {
        content: "";
        position: absolute;
        bottom: .55rem;
        left: 0;
        width: 100%;
        height: .2rem;
        border: .2rem solid $btc;
      }
    }
  }
}

@media only screen and (max-width: 768px) {
  .hero {
    padding: 18vh 0;

    h3 {
      font-size: 2.2rem;
      line-height: 2.2rem;

      span:after {
        bottom: .35rem;
        height: .15rem;
        border-width: .15rem;
      }
    }
  }
}