.c-button__group--sub a {
  font-size: 0;
  background: none;
  border: none;
}

.c-button__group--sub a:before {
  font-size: 14px;
  content: "ホームへ戻る";
  margin: 0 7px;
  color: #35454c;
  text-decoration: none;
  border: none;
  white-space: nowrap;
  display: inline-block;
  vertical-align: middle;
  -webkit-appearance: none;
  background: #eff2f4;
  line-height: 1;
  border: none;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  cursor: pointer;
  box-shadow: inset 0 -0.1em 0 rgba(0, 0, 0, 0.1);
  padding: .75em 1.5em;
}

.c-form__title--must {
  color:#ff0000;
}