Someone

/*#header
H1 {
    text-align:center;
    //background-color: red;
    background-size: 10px;
    background-image: url(logo.png);
    background-origin:border; 
    */
    /*background-attachement : fixed;
    background-position : 100% 100%;*/
    /*background-repeat : no-repeat;*/
    
   /*no-repeat left;  : no-repeat;
    background-size: a
    background:red;
    margin-left:auto;
    margin-right:auto;*/
    }
/*#coeur
 {  background-color: red;
    background-image: url(logo.png);
    background-size: 10% auto;
  }
*/

body {
margin: 0;
padding: 0;
background: white;
font: 80% verdana, arial, sans-serif;
text-align: center;
}

#all{
	width: 50%;
	margin-left: auto;
	margin-right: auto;
}

#header{
    height: 50px;
    margin-left: auto;
    margin-right: auto;
}
#header 
H1{
text-align:center;
background-color: red;
}

#menubar {
      border-top: 2px solid #e6e6e6;
      border-right: 2px solid #b1b1b1;
      border-bottom: 2px solid #b1b1b1;
      border-left: 2px solid #e6e6e6;
      background-color: #ccc;
      color: #000;
      height: 1.4em;
      line-height: 1.2em;
      width: 100%;
    }
    
    .menu {
      width: auto;
      float: left;
      padding: 0.1em 3em 0.1em 0.5em;
      cursor: default;
    }
    
    .menu ul {
      display: none;
      position: absolute;
      background-color: #e6e6e6;
      color: black;
      list-style: none;
      margin: 0.1em 0 0 0;
      padding: 0;
    }
    
    .menu ul li {
      display: block;
      padding: 0.2em;
    }
    
    div.menu:hover ul {
      display: block;
      margin: 0;
      padding: 0;
    }

    div.menu ul li:hover {
      background-color: #ccf;
    }

/*

    Mise en forme des menus.

*/

dl, dt, dd, ul, li {
margin: 0;
padding: 0;
list-style-type: none;
}
#menu {

    z-index:100;
    background:blue;
}
#menu dl {
float: left;
//width: auto;
margin: 0 1px;
}
#menu dt {
cursor: pointer;
text-align: center;
font-weight: bold;
background: red;
border: 1px solid gray;
}
#menu dd {
border: 1px solid gray;
}
#menu li {
height: 12px;
text-align: center;
background: #fff;
}
#menu li a, #menu dt a {
color: #000;
text-decoration: none;
display: block;
height: 20px;//100%;
border: 0 none;
}
#menu li a:hover, #menu dt a:hover {
background: #eee;
}
/*
    Mise en forme de la page principale
*/

#site {
background-image: url(logo.png);
background-position : 100% 100%;
background-repeat : no-repeat;
position: relative;
z-index: 2;
top : 70px;
left : 10px;
color: #000;
background-color: #ddd;
padding: 5px;
border: 1px solid gray; 
}

a {text-decoration: none;
color: black;
color: #222;
}