node-red/packages/node_modules/@node-red/editor-client/src/sass/tab-help.scss

.red-ui-sidebar-help-stack {
    // height: calc(100% - 39px);
}
.red-ui-help-search {
    border-bottom: 1px solid var(--red-ui-secondary-border-color);
}

.red-ui-sidebar-help-toc {
    .red-ui-treeList-label {
        font-size: 13px;
        padding: 2px 0;
        overflow: hidden;
        white-space: nowrap;
    }

}
#red-ui-sidebar-help-show-toc {
    i.fa-angle-right {
        transition: all 0.2s ease-in-out;
    }
    &.selected {
        i.fa-angle-right {
            transform: rotate(90deg);
        }
    }

}