Placer deux div-éléments l'un à côté de l'autre

In this solution we use display:
flex style property for our wrapping <div> element, 
so in both children divs we can set flex: property 
value with 1 to display two equal size <div> elements n
ext to each other. 

ex :

<html>
<head>
  <style>   
 
    div {
    	border: 1px solid red;
    }
    
    div.container {
    	display: flex;  /* <---------- required */
    }
    
    div.child {
    	flex: 1;  /* <---------------- required */
    }
    
  </style>
</head>
<body>
  <div class="container">
    <div class="child">1</div>
    <div class="child">2</div>
  </div>
</body>
</html>
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