.panes {
  display: flex;
  flex-grow: 1;
  box-sizing: border-box;
  position: relative;
  flex-direction: row;
  align-items: stretch;
}

.pane {
  overflow: hidden;
  flex-grow: 1;
  position: relative;
  overflow: scroll;
  border-right: 1px solid #ccc;
}

.paneItems {
  display: block;
  list-style: none;
  margin: 0;
  padding: 0;
  overflow: scroll;
}

.paneItem {
  line-height: 3em;
  border-bottom: 1px solid #ccc;
}

.paneItemLink {
  display: block;
  padding: 0 1em;
  text-decoration: none;
  color: inherit;
}

.paneItemLink:hover {

}

.activePaneItemLink {
  composes: paneItemLink;
  font-weight: 700;
  background-color: #ccc;
}

.panes {

}

.panes {
  display: flex;
  flex-grow: 1;
  box-sizing: border-box;
  position: relative;
  flex-direction: row;
  align-items: stretch;
}

.pane {
  overflow: hidden;
  flex-grow: 1;
  position: relative;
  overflow-y: auto;
  border-right: 1px solid #ccc;
}

.paneItems {
  display: block;
  list-style: none;
  margin: 0;
  padding: 0;
}

.paneItem {
  line-height: 3em;
  border-bottom: 1px solid #ccc;
}

.paneItemLink {
  display: block;
  padding: 0 1em;
  text-decoration: none;
  color: inherit;
}

.paneItemLink:hover {

}

.activePaneItemLink {
  composes: paneItemLink;
  font-weight: 700;
  background-color: #ccc;
}

.panes {

}

Fix scroll styling on non-Mac devices
Fix scroll styling on non-Mac devices
