Why are svg icons rendered black?

Question

HTML

Good day! Please tell me why when displaying icons through the construction

<svg class="ico">
  <use xlink:href="app/img/ico/icons.svg#icoFb"></use>
</svg>

Icons are displayed in black! Although they should be colored. When exporting from illustrator, it is colored, I opened it and everything is ok.
Website - In the header of the site, see 2 black circles.
This is what the icons should look like:

Answer 1

Where do you get the information that this is how it should work? You are the thousandth person asking this question.
The documentation says here :
Insert svg as part of the html document, then you will see your icon through

<svg class="ico">
  <use xlink:href="#icoFb"></use>
</svg>

In IE11