.panel {
  /* Default transition for closing - linear and immediate */
  transition: width 0.15s linear, transform 0.2s ease, box-shadow 0.2s ease, filter 0.2s ease;
  width: var(--panel-width);
  height: 100%;
  position: relative;
  cursor: pointer;
  }

.panel:not(.expanded):hover {
  transform: scale(1.02);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
  filter: brightness(1.1);
  }

.panel.expanding {
  /* Smooth transition for opening */
  transition: width var(--transition-duration) var(--transition-timing);
  }

  .panel h1 {
  position: absolute;
  top: 50%;
  left: 50%;
  color: white;
  white-space: nowrap;
  margin: 0;
  }

  .left-panel h1 {
  transform: translate(-50%, -50%) rotate(-90deg);
  font-family: "Archivo Black", serif;
  font-size: clamp(1.5rem, 4.5vw, 3rem);
  }

  .right-panel h1 {
  transform: translate(-50%, -50%) rotate(90deg);
  font-family: "Archivo Black", serif;
  font-size: clamp(1.5rem, 4.5vw, 3rem);
  }

  .panel h1.slide-left,
  .panel h1.slide-right {
  opacity: 1;
  }

  .left-panel.expanded h1 {
  opacity: 0;
  font-family: "Archivo Black", serif;
  font-size: 75px;
  }

  .right-panel.expanded h1 {
  opacity: 0;
  font-family: "Archivo Black", serif;
  font-size: 75px;
  }

  .left-panel {
  background-color: #333;
  background-image: linear-gradient(135deg, #333 0%, #444 100%);
  border-right: 2px solid rgba(255, 255, 255, 0.1);
  }

  .left-panel:not(.expanded):hover {
  background-image: linear-gradient(135deg, #444 0%, #555 100%);
  border-right: 2px solid rgba(255, 255, 255, 0.2);
  }

  .right-panel {
  background-color: #555;
  background-image: linear-gradient(135deg, #555 0%, #666 100%);
  margin-left: auto;
  border-left: 2px solid rgba(255, 255, 255, 0.1);
  }

  .right-panel:not(.expanded):hover {
  background-image: linear-gradient(135deg, #666 0%, #777 100%);
  border-left: 2px solid rgba(255, 255, 255, 0.2);
  }

  .panel-content {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  overflow-y: auto;
  opacity: 0;
  pointer-events: none;
  visibility: hidden;
  }

  .panel-content {
  transition: opacity 0.2s ease-out, visibility 0.025s ease-out;
  }

  .panel-content.visible {
  transition: opacity .15s cubic-bezier(0.7, 0, 0.84, 0), visibility .025s cubic-bezier(0.7, 0, 0.84, 0);
  opacity: 1;
  pointer-events: auto;
  visibility: visible;
  }

  .panel p{
  margin: 0;
  color: white;
  text-align: center;
  }

  .panel.expanded {
  cursor: default;
  transform: none;
  box-shadow: none;
  filter: none;
  }

  .panel.expanded:hover {
  transform: none;
  box-shadow: none;
  filter: none;
  }

  .left-panel.expanded,
  .right-panel.expanded {
  width: calc(100% - var(--panel-width));
  background-image: none;
  border: none;
  }

  .left-panel.expanded {
  background-color: #2a2a2a;
  }

  .right-panel.expanded {
  background-color: #2a2a2a;
  }