title: Bootstrap 4 buttons example: where does the space between buttons is coming from?
body: <p>I have tried to inspect a "Buttons" example from Bootstrap 4. They have a nice-looking row of buttons, like this:</p>
  
  <p><a href="https://i.stack.imgur.com/OnQ3U.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OnQ3U.png" alt="enter image description here"></a></p>
  
  <p><a href="http://getbootstrap.com/docs/4.0/components/buttons/" rel="noreferrer">http://getbootstrap.com/docs/4.0/components/buttons/</a></p>
  
  <p>But I don't understand, where does the space between buttons is coming from.</p>
  
  <p><a href="https://i.stack.imgur.com/mjmXs.png" rel="noreferrer"><img src="https://i.stack.imgur.com/mjmXs.png" alt="enter image description here"></a></p>
  
  <p>This is not margin, not flex-box aligning, not a transparent border.
  So, how it works? Actually, I disabled all the styles in dev-tools, but that space did not disappear.</p>