.sub-mainview__page-title {
  position: relative;
}

.sub-mainview__page-sub-title {
  position: absolute;
  top: 3em;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.5em;
  width: 100%;
  text-align: center;
}

.backnumber__list {
  padding: 3rem 0 0 0;
}

.backnumber__item {
  list-style: none;
  display: flex;
}
.backnumber__item:not(:last-of-type) {
  margin-bottom: 2rem;
}

.backnumber-item__date,
.backnumber-item__title {
  color: #0070c0;
  min-width: 95px;
  flex-shrink: 0;
  font-size: 15px;
  line-height: 1.5;
}

.backnumber-item__date {
  width: 10%;
}

.backnumber-item__content {
  width: 85%;
}

.backnumber-item__category {
  color: #c55a11;
}

@media screen and (max-width: 768px) {
  .backnumber__item {
    flex-direction: column;
  }
  .backnumber__item:not(:last-of-type) {
    margin-bottom: 1rem;
  }

  .backnumber-item__date,
  .backnumber-item__title {
    font-size: 4vw;
  }

  .backnumber-item__date {
    margin-bottom: 0.5em;
  }

  .backnumber-item__content {
    width: 100%;
  }

  .backnumber-item__text {
    font-size: 3.73333vw;
  }
}