How to set minimum height to the 100% of the viewing screen and half of the page?

Question

I have single page site where 1st part main part which should be 100% of the viewers screen/browser size and the 2nd part should be below the viewing area, so when a user clicks on a link , the page gets scrolled down to the second part .

how do i achieve this., i have tried this so far, but its not setting min-height yo 100%

HTML:

<div class="container">
<div class="firsthalf">
this is the first part of the site
<a href="#help"> <i class="fa fa-question-circle fa-lg"></i>
<div class="notice">this is aligned to bottom of first half
</div></div>   
</div>    

<div class="container">
<div id="help" class="secondhalf">
<div class="col-md-8 col-md-offset-2">
<div class="well">
we are in second part of the site
</div>
<a href="#top" class="btn btn-default"><i class="fa fa-arrow-up "></i> Top</a>
</div>
</div>
</div>

CSS:

body, html {
  height: 100%;
}
.firsthalf{
height:100%;
}
.notice{
margin-bottom:0%;
padding-bottom:5px;
}
.secondhalf{
margin-top:25%;
margin-bottom:50%;
padding-top:25px;
min-height:50%;

}

http://jsfiddle.net/4yk2q/

Answer 1

Play with position: relative; and position: absolute; ... they are your friend in this case...

Solution demo

body, html {
    height: 100%;
}
.container {
    height:100%;   /* first make container full height */
}
.firsthalf {
    height:100%;
    border:1px solid #000;
    position: relative; /* make parent div relative */
}
.notice {
   padding-bottom:5px;
   position: absolute; /* this does the base line trick */
   bottom: 0;
   right: 0;
}

Answer 2

viewport height (vh) You are looking for height:50vh; or height: 100vh;

There are a few options you may find useful:

vh (viewport height) vw (viewport width) vmin (viewport minimum length) vmax (viewport maximum length)

http://stanhub.com/how-to-make-div-element-100-height-of-browser-window-using-css-only/

.secondhalf{
margin-top:25%;
margin-bottom:50%;
padding-top:25px;
height:50vh;

}

Edit: make sure it is supported by the browsers you need to support. http://caniuse.com/#feat=viewport-units