[inner div full height/width outer div] #html #css #div #fullwidth #fullheight

fullsize.css

html,body{
    height: 100%;
}
.outer{
    background-color:blue;
    height: 80%; border:red solid 2px;
    display: table;
    width:100%
}
.inner-title{
    background-color:red;
    display:table-row; 
    width:100%
}
.inner-content{
    background-color:grey;
    display:table-row;
    width:100%;
     height:100%
}

fullsize.html

<div class="outer">
    <div  class="inner-title">
        THIS IS MY TITLE
    </div>
    <div class="inner-content">
        CONTENT AREA
    </div>
</div>