JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">
    This is a header.
</div>
<div class="colmask doublepage">
    <div class="colleft">
        <div class="col1">
            <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
        </div>
        <div class="col2">
    <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
        </div>
    </div>
</div>
<div id="footer">
        This is a footer.
</div>

CSS

#header {
    background: lightgreen;
    clear:both;
    float:left;
    width:100%;
}
.colmask {
    clear:both;
    float:left;
    width:100%;            
    overflow:hidden;
}
.colleft {
    float:left;
    width:100%;
    position:relative;
}
.col1,.col2{
    float:left;
    position:relative;
    padding:0 0 1em 0;
    overflow:hidden;
}

.doublepage {
    background: lightblue;   /* right column background colour */
}
.doublepage .colleft {
    right:50%; /* right column width */
    background: salmon; /* left column background colour */
}
.doublepage .col1 {
    width:46%; /* left column content width (column width minus left and right padding) */
    left:52%; /* right column width plus left column left padding */
}
.doublepage .col2 {
    width:46%; /* right column content width (column width minus left and right padding) */
    left:56%; /* (right column width) plus (left column left and right padding) plus (right column left padding) */
}
#footer {
    background: pink;
    clear:both;
    float:left;
    width:100%;
}