item-message-pane { display: flex; flex-direction: column; .custom-head { display: flex; flex-direction: row; align-self: stretch; gap: 6px; padding: 6px 8px; background: var(--material-toolbar); border-bottom: var(--material-panedivider); height: 28px; &:empty { display: none; } button { height: 26px; margin: 0; flex-grow: 1; } } #zotero-item-pane-groupbox { flex: 1; border-width: 0; } }