.hidden-items {
  overflow: hidden;
  max-height: 0;
  transition: max-height 1.2s ease;
}

.view-more-btn {
  border: solid 1px #333;
  padding: 1em 2em;
  margin: 3em auto 0 auto;
  display: block;
}

.arrow {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-right: 1px solid #333333;
  border-bottom: 1px solid #333333;
  transform: rotate(45deg); /* ∨ の形 */
  transition: transform 0.3s ease;
  margin-left: 8px;
  vertical-align: middle;
  position: relative;
  top: -4px; /* 視覚的な中央補正 */
}

.arrow.open {
  transform: rotate(-135deg); /* ∧ の形 */
  top: 0px; /* 開いたときの補正 */
}