zoom buttons does not show

[SajjadKharrazi]

https://i.stack.imgur.com/8vCz9.jpg
<openlayers ol-center="center" height="345px" width="560px"> <ol-marker ol-marker-properties="coords"><ol-marker> </openlayers>
how can i show them? plus and minus

[jsruok]

I couldn't see zoom buttons at first, either. On a closer inspection they were there, right beneath the canvas. And when I included the Open Layers css (ol.css), they appeared over the canvas as expected.