.history_head--buttons {
  display: flex;
  justify-content: flex-start;
  gap: 2rem;
  border-bottom: 2px solid #ddd;
}
@media (max-width: 768px) {
  .history_head--buttons {
    flex-direction: column;
    align-items: center;
    gap: 1rem;
  }
}
.history_head--buttons .history--button {
  padding: 1rem 2rem;
  font-size: 1.8rem;
  background: #f5f5f5;
  border: 2px solid #ddd;
  border-bottom: none;
  border-radius: 8px 8px 0 0;
  cursor: pointer;
  transition: all 0.3s ease;
  color: #666;
  position: relative;
  top: 2px;
  margin-bottom: -2px;
}
.history_head--buttons .history--button:hover {
  background: #eee;
  color: #333;
}
.history_head--buttons .history--button.is-active {
  background: #fff;
  color: #3a3a3a;
  border-color: #3a3a3a;
  font-weight: bold;
  z-index: 1;
}

.history-section {
  display: none;
}
.history-section.is-visible {
  display: block;
}
.history-section dl {
  width: 100%;
  padding: 1rem 0;
  font-size: 2rem;
  display: flex;
  justify-content: flex-start;
  align-items: stretch;
}
@media (max-width: 768px) {
  .history-section dl {
    flex-direction: column;
    gap: 1rem;
  }
}
.history-section dt {
  width: 7em;
  font-weight: bold;
  line-height: 1.5em;
  text-align: center;
  flex-shrink: 0;
  border-bottom: 1px solid var(--gray);
}
.history-section dd {
  border-bottom: 1px solid var(--light-gray);
}
@media (max-width: 768px) {
  .history-section dd {
    border-bottom: none;
  }
}
.history-section dd ul {
  padding-left: 4rem;
}
.history-section dd ul li {
  margin-bottom: 1.5rem;
  line-height: 1.5em;
  list-style-type: disc;
}
.history-section dd ul li:nth-last-of-type() {
  margin-bottom: 0;
}
.history-section dd ul li a {
  color: var(--blue);
  text-decoration: underline;
}
.history-section dd ul li a:hover {
  opacity: 0.7;
}