Grid met css3's calc()

grid.css

.container {
	max-width: 1140px;
	margin-left: auto;
	margin-right: auto;
}

.row:before,
.row:after {
	content: " ";
	display: table;
}
.row:after {
	clear: both;
}

.col {
	float: left;
	box-sizing: border-box;
}

.col-1 {
	width: calc(1/12 * 100%);
}

.col-2 {
	width: calc(2/12 * 100%);
}

.col-3 {
	width: calc(3/12 * 100%);
}

.col-4 {
	width: calc(4/12 * 100%);
}

.col-5 {
	width: calc(5/12 * 100%);
}

.col-6 {
	width: calc(6/12 * 100%);
}

.col-7 {
	width: calc(7/12 * 100%);
}

.col-8 {
	width: calc(8/12 * 100%);
}

.col-9 {
	width: calc(9/12 * 100%);
}

.col-10 {
	width: calc(10/12 * 100%);
}

.col-11 {
	width: calc(11/12 * 100%);
}

.col-12 {
	width: 100%;
}

voorbeeld.html

<div class="container">
    <div class="row">
        <div class="col col-6">
            
        </div>
        <div class="col col-6">
            
        </div>
    </div>
    
    <div class="row">
        <div class="col col-4">
            
        </div>
        <div class="col col-4">
            
        </div>
        <div class="col col-4">
            
        </div>
    </div>
</div>