@charset "utf-8";
/* CSS Document */
body{
    margin: 0;
    padding: 0;
}
section{
    width: 600px;
    height: 250px;
    background-color: yellow;
    border: 2px dashed black;
    margin: auto;
    position: relative;
}
#box1{
    background-color: orange;
    width: 200px;
    height: 200px;
    border: 2px solid black;
    position: absolute;
    right: 50px;
    bottom: -100px;
    z-index: -100;
    /*par défaut z-index:0. la boite (-100) sera en dessous la section (0)*/
    border-radius: 50%;
}
#box2{
    background-color: orange;
    width: 200px;
    height: 200px;
    border: 2px solid black;
    position: absolute;
    left: 0px;
    bottom: -50px;
    z-index: 100;
    /*par défaut z-index:0. la boite (100) sera au dessus la section (0)*/

}