@media (max-width: 640px) {
  #topbar {
    overflow-x: auto;
    overflow-y: hidden;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    gap: 6px;
    padding: 0 8px;
  }

  #topbar::-webkit-scrollbar {
    display: none;
  }

  #topbar>* {
    flex-shrink: 0;
  }

  #topbar .tb-btn {
    font-size: 0;
    gap: 0;
    padding: 3px 8px;
  }

  #topbar .tb-btn svg {
    width: 15px;
    height: 15px;
  }

  #topbar #theme-toggle {
    font-size: 11px;
  }

  #topbar button[onclick="addSection()"] {
    display: none;
  }

  #mob-add-section {
    display: flex;
  }

  #topbar [style*="flex:1"] {
    display: none;
  }

  #main {
    flex-direction: column;
    overflow-y: auto;
  }

  #left,
  #right {
    width: 100%;
    border-right: none;
    flex-shrink: 0;
  }

  #left {
    border-bottom: 1px solid var(--bd-inner);
    padding: 10px;
    gap: 8px;
  }

  #display-box {
    aspect-ratio: 2/1;
    width: 100%;
  }
}