It would be good if you included a drawing that showed what you want the layout to look like and list any other requirements that you have.
I took a wild guess, anyway, and used display:table/table-cells for the columns. The header and footer are display:table because the classes were written in series in your original code. They could be written separately as ordinary block divs with no width applied, if you prefer.
This is a “working page”. Copy it to a file and open the file in your browser to see how it works.
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>template</title>
<!--
https://www.sitepoint.com/community/t/how-to-align-three-blocks-one-after-another-in-css/217865
vngx
-->
<style type="text/css">
html {
-webkit-box-sizing:border-box;
-moz-box-sizing:border-box;
box-sizing:border-box;
}
*,*:before,*:after {
box-sizing:inherit;
}
body {
background:blue;
}
.outer {
width:80%;
margin:10% auto 0;
}
.header,.main_block,.footer {
display:table;
width:100%;
table-layout:fixed;
background-color:white;
}
.header {
height:1em; /* TEST height */
padding:0 .5em;
background-color:#fdf;
}
.footer {
height:1em; /* TEST height */
padding:0 .5em;
background-color:#ddd;
}
.masterBottomOne,.masterBottomTwo,.masterBottomThree,.masterBottomFour,.masterBottomFive {
display:table-cell;
vertical-align:top;
padding:0 .5em;
}
.masterBottomOne {background-color:#def;}
.masterBottomTwo {background-color:#dfd;}
.masterBottomThree {background-color:#fed;}
.masterBottomFour {background-color:#dff;}
.masterBottomFive {background-color:#ffd;}
</style>
</head>
<body>
<div class="outer">
<div class="header">
<p>Header</p>
</div>
<div class="main_block">
<div class="masterBottomOne">
<p>This is Master One Content</p>
<p>This is Master One Content</p>
<p>This is Master One Content</p>
<p>This is Master One Content</p>
<p>This is Master One Content</p>
<p>This is Master One Content</p>
</div>
<div class="masterBottomTwo">
<p>This is Master Two Content</p>
<p>This is Master Two Content</p>
<p>This is Master Two Content</p>
<p>This is Master Two Content</p>
<p>This is Master Two Content</p>
</div>
<div class="masterBottomThree">
<p>This is Master Three Content</p>
<p>This is Master Three Content</p>
<p>This is Master Three Content</p>
<p>This is Master Three Content</p>
<p>This is Master Three Content</p>
</div>
<div class="masterBottomFour">
<p>This is Master Four Content</p>
<p>This is Master Four Content</p>
<p>This is Master Four Content</p>
<p>This is Master Four Content</p>
<p>This is Master Four Content</p>
</div>
<div class="masterBottomFive">
<p>This is Master Five Content</p>
<p>This is Master Five Content</p>
<p>This is Master Five Content</p>
<p>This is Master Five Content</p>
<p>This is Master Five Content</p>
</div>
</div>
<div class="footer">
<p>This is Admin Footer</p>
</div>
</div>
</body>
</html>