grid system using http://www.responsivegridsystem.com/

index.html

<div class="section group">
	<div class="col span_1_of_6">
	1 of 6
	</div>
	<div class="col span_1_of_6">
	1 of 6
	</div>
	<div class="col span_1_of_6">
	1 of 6
	</div>
	<div class="col span_1_of_6">
	1 of 6
	</div>
	<div class="col span_1_of_6">
	1 of 6
	</div>
	<div class="col span_1_of_6">
	1 of 6
	</div>
</div>
<hr>
<div class="section group">
  <div class="col span_3_of_6">3 of 6</div>
  <div class="col span_3_of_6">3 of 6</div>
</div>
<div class="section group">
  <div class="col span_1_of_6">
    <p>1 of 6</p>
    <p>This is</p>
    <p>a tall and</p>
    <p>skinny col.</p>
  </div>
  <div class="col span_5_of_6">
    <div class="section group">
      <div class="col span_3_of_5">3 of 5</div>
      <div class="col span_1_of_5">1 of 5</div>
      <div class="col span_1_of_5">1 of 5</div>
    </div>
  </div>
</div>
<div class="section group">
  <div class="col span_3_of_6">3 of 6</div>
  <div class="col span_1_of_6">1 of 6</div>
  <div class="col span_1_of_6">1 of 6</div>
</div>

style.css

.col {
  background: rgba(204, 204, 204, 0.85);
}
 
/*  SECTIONS  */
.section {
	clear: both;
	padding: 0px;
	margin: 0px;
}
 
.section .section .col {
  margin-top: 0;
  margin-bottom: 0;
}
 
/*  COLUMN SETUP  */
.col {
	display: block;
	float:left;
	margin: 1% 0 1% 1%;
}
.col:first-child { margin-left: 0; }
 
 
/*  GROUPING  */
.group:before,
.group:after {
	content:"";
	display:table;
}
.group:after {
	clear:both;
}
                                               
					
/*  GRID OF FIVE  */
.span_5_of_5 {
	width: 100%;
}
.span_4_of_5 {
	width: 79.8%;
}
.span_3_of_5 {
	width: 59.6%;
}
.span_2_of_5 {
	width: 39.4%;
}
.span_1_of_5 {
	width: 19.2%;
}
 
/*  GRID OF SIX  */
.span_6_of_6 {
	width: 100%;
}
 
.span_5_of_6 {
  	width: 83.16%;
}
 
.span_4_of_6 {
  	width: 66.33%;
}
 
.span_3_of_6 {
  	width: 49.5%;
}
 
.span_2_of_6 {
  	width: 32.66%;
}
 
.span_1_of_6 {
  	width: 15.83%;
}
 
/*  GO FULL WIDTH AT LESS THAN 480 PIXELS */
 
@media only screen and (max-width: 480px) {
	.col { 
		margin: 1% 0 1% 0%;
	}
}
 
@media only screen and (max-width: 480px) {
	.span_5_of_5 {
		width: 100%; 
	}
	.span_4_of_5 {
		width: 100%; 
	}
	.span_3_of_5 {
		width: 100%; 
	}
	.span_2_of_5 {
		width: 100%; 
	}
	.span_1_of_5 {
		width: 100%;
	}
 
  .span_6_of_6 {
		width: 100%; 
	}
	.span_5_of_6 {
		width: 100%; 
	}
	.span_4_of_6 {
		width: 100%; 
	}
	.span_3_of_6 {
		width: 100%; 
	}
	.span_2_of_6 {
		width: 100%; 
	}
	.span_1_of_6 {
		width: 100%;
	}
}