Испытание: строим сетку 100% (укажите на ошибки в коде)

Курсы §15. Сетки
1

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

body {
width: 450px;
height: 335px;
font-family: “Arial”, sans-serif;
font-size: 10px;
color: white;
}

.head {
background: #34495e;
padding-top: 10px;
}

.head-header {
background: #c0392b;
width:345px;
margin-left:auto;
margin-right:auto;
padding: 5px 0px 18px 5px;
margin-bottom: 10px;
}

.head-menu {
background: #3498DB;
width:395px;
padding: 5px 0px 18px 55px;
margin-bottom: 10px;
}

.head-promo {
background: #34495e;
margin-bottom: 10px;
padding-bottom: 10px;
}
.promo-1 {
background: #c0392b;
width: 165px;
min-height: 55px;
padding-left:5px;
padding-top:5px;
}
.head-promo-1 {
float: left;
margin-left: 50px;
}
.head-promo-2 {
float: right;
margin-right: 50px;
}

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

.main {
margin-bottom: 10px;
}

.main-it {
background: #3498DB;
min-height: 105px;
padding-left:5px;
padding-top:5px;
}

.main-Left{
float: left;
width: 65px;
margin-left: 50px;
margin-right: 10px;
}

.main-Main{
float: left;
width: 185px;
}

.main-Right{
float: right;
width: 65px;
margin-right: 50px;
}

.Footer {
background: #34495e;
padding-bottom:30px;
padding-left:55px;
padding-top:5px;
}

"

<body>
    <div class="head">
        <div class="head-header">
            Header
        </div>
        <div class="head-menu">
            Menu
        </div>
        <div class="head-promo clearfix">
            <div class="head-promo-1 promo-1 ">
                Promo 1
            </div>
            <div class="head-promo-2 promo-1 ">
                Promo 2
            </div>
        </div>
    </div>
    <div class="main clearfix">
        <div class="main-Left main-it">Left</div>
        <div class="main-Main main-it"> Main</div>
        <div class="main-Right main-it">Right</div>
    </div>
    <div class="Footer">
        Footer
    </div>
</body>