title: Tabs border with triangle with CSS
body: <p><img src="https://i.stack.imgur.com/OgDgB.png" alt="Tab border CSS3"></p>
  
  <p>I am trying to represent my HTML/CSS tab like on the picture.</p>
  
  <p>I have already tried lots of things with border-radius without any success.
  Do you have any tracks so that I can reproduce my tabs like the picture only with CSS?</p>