Add small logo for a custom Kibana app

[trex]

Kibana 5.2.2
Elasticsearch 5.2.2
Server OS: Ubuntu v15
Browser: Chrome Version 58.0.3029.96 (64-bit) and Firefox 47.0
Browser OS: Ubuntu v15

I want to display a big logo if the left menu bar is open and a small one if the bar is collapsed. Now, I use the code from this guide to display the big logo:

// in plugin/public/main.js
import uiChrome from 'ui/chrome';
import logoUrl from 'plugins/facechimp/assets/banner.png';

uiChrome.setBrand({
  logo: `url(${logoUrl}) center no-repeat`
});

In order to have the small logo displayed, I modified code to this:

import smallLogo from 'plugins/facechimp/assets/smallBanner.png';
uiChrome.setBrand({
  logo: `url(${logoUrl}) center no-repeat`,
  smallLogo: `url(${smallLogo}) center no-repeat`
});

But the small logo is not displayed when the menu bar is collapsed, there is always the big logo.
How could the small logo be displayed when the menu bar is collapsed?