Wordpress different results when calling a function. Why?

Question

WordPress

Good afternoon! Tell me please. Why can there be such a bug: In different places of the template, a function is called.
get_avatar();
In one case, it returns the path to the avatar as it should be, and everything is displayed correctly. And in another line like

<img src="http://www.xxx.ru/wp-content/plugins/user-avatar/user-avatar-pic.php?src=http://www.xxx.ru/wp-content/uploads/avatars/1/1448046762-bpfull.jpg&amp;w=150&amp;id=1&amp;random=1448046762" alt="" class=" avatar  avatar-150  photo user-1-avatar" height="150" width="150">

And accordingly nothing is displayed. Why can this be? I've already broken my head...

Answer 1

The distribution has a theme.less LESS file.
Add the necessary components to it with @import, and edit them for yourself there.
As a result, you have a clean bootstrap + your own theme for it.

Answer 2

You can't use Bootstrap, you can use Bootstrap.
You can change the style of Bootstrap, as you said, through LESS or regular css.