title: How to force position absolute with 100% width to fit into parent div with padding?
body: <p>I have 2 divs, an outer div which is a parent and a child div. The outer div is position relatives with padding 20px for left and right while the child is position absolute with 100% widthg. How can I force the child which is position absolute to be within the parent, ie respecting the padding 20px (inside parent and within the 20px padding)</p>
  
  <p>I've done the example here: <a href="http://www.bootply.com/nyGZzTVY8v" rel="noreferrer">http://www.bootply.com/nyGZzTVY8v</a></p>
  
  <p>I've read about box-sizing but I still don't understand how to implement it correctly. Tried putting it on the box1 class and nothing happen, tried putting on the box2 class and nothing happen also.</p>
  
  <p>thanks in advance.</p>
  
  <p>Additional Note: It has to be responsive ie I do not know the size of the parent div thus the 100% for the child div.</p>