title: send an image back to the background color in css
body: <p>I have a navigation bar which has a background color.</p>
  
  <p><img src="https://i.stack.imgur.com/fxSnV.jpg" alt="enter image description here"></p>
  
  <p>now I load an image to each elements of bar. </p>
  
  <p>Now I want to send 50% of images behind to the bar and 50% shows above the bar.</p>
  
  <p>how this is possible?</p>
  
  <p><img src="https://i.stack.imgur.com/K791C.png" alt="here is picture of my page:"></p>
  
  <p>But I want something like this:</p>