Испытание: строим сетку [27/32] . 100%, подскажите, что лишнее?

Курсы §15. Сетки
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HTML

<html lang="ru">
    <head>
        <title>Испытание: строим сетку</title>
        <meta charset="utf-8">
    </head>
    <body>
        <div class="container-header">
            <div class="layout-positioner">
            <div class="header">Header</div>
            <div class="menu ">Menu</div>
            <div class = "promo1 column1">Promo 1</div>
            <div class = "promo2 column1">Promo 2</div>
         </div>
         </div>
        <div class="container-main clearfix">
            <div class="layout-positioner">
            <div class="left column2">Left</div>
            <div class="main column2">Main</div>
            <div class="right column2">Right</div>
        </div>
        </div>
        <div class="footer">
            <div class="layout-positioner">Footer</div>
            </div>
    </body>
</html>!

CSS

html,
body {
margin: 0;
padding: 0;
}

body {
width: 450px;
height: 335px;
font-family: “Arial”, sans-serif;
font-size: 10px;
color: white;
}
.container-header {
width:auto;
min-height:150px;
background:#34495e;
padding:10px 0;
margin-bottom:10px;
}
.header{
background:#c0392b;
margin: 0 50px 10px;
height:25px;
padding:5px;
}

.menu {
background: #3498DB;
margin-bottom:10px;
height:25px;
padding:5px 55px;;
}

.promo1 {
float:left;
width:160px;
height:50px;
margin-left:50px;
padding:5px;
background:#c0392b;
}

.promo2 {
width:160px;
height:50px;
margin-left:230px;
padding:5px;
background:#c0392b;
}

.container-main {
margin-bottom:10px;

}

.column2 {
float:left;
width:350px;
margin-left:50px;
min-height:90px;
}

.clearfix::after {
display: table;
content: “”;
clear: both;
}

.left{
width: 60px;
height:100px;
padding:5px;
background: #3498DB;
}
.main{
width:180px;
height:100px;
margin-left:10px;
padding:5px;
background: #3498DB;
}
.right {
float:right;
width: 60px;
height:100px;
margin-right:50px;
margin-left:10px;
padding:5px;
background: #3498DB;
}
.footer{
background:#34495e;
height:25px;
padding:5px 55px;
}
.layout-positioner {
width:450px;
margin:0 auto;
}

.layout-positioner::after {
display: table;
content: “”;
clear: both;
}

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