title: D3js: blocks with text inside & hover to show more text
body: <p>I'm new to D3js. I want to have some basic blocks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/0VJXK.png" alt="enter image description here"></p>
  
  <p>The text in the block should be taken from a JSON file. If the block is hovered, it will show:</p>
  
  <p><img src="https://i.stack.imgur.com/8h85Z.png" alt="enter image description here"></p>
  
  <p>Any suggestions on how to do this? Or are there any available tutorials on this? Thanks in advance! </p>