title: Create special CSS Shape
body: <p>I would like to create a special CSS Shape for my header. The have to look like the first speech bubble from this website <a href="http://nicolasgallagher.com/pure-css-speech-bubbles/demo/" rel="nofollow">http://nicolasgallagher.com/pure-css-speech-bubbles/demo/</a> but, the arrow has to be a half circle and the half circle has to be always in the middle. This is for my header so even if the shape is 100% of the browser's length the circle has to stay in the middle of the browser, also when I resize the browser window.</p>
  
  <p>So my question is, is that possible and if so, how?</p>