If you want to scale the content in a specific height you can use transform: scale(); and media queries with max-height:
First the HTML
<div class="wrapper">
        <div class="main">
            <h2>Hi my name is Shashank</h2>
            <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Omnis, fugiat, aut, repellendus architecto repellat at soluta perspiciatis suscipit quia error tempora ea aliquid saepe beatae id excepturi cupiditate esse ex.</p>
            <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Omnis, fugiat, aut, repellendus architecto repellat at soluta perspiciatis suscipit quia error tempora ea aliquid saepe beatae id excepturi cupiditate esse ex.</p>
        </div>
</div>
Then the CSS
html, body {
  background: #333;
  padding: 0px;
  margin: 0px;
  color: #222222;
  height: 100%;
  width:100%;
  display: table;
}
.wrapper {
  margin: 0 auto;
  position: relative;
  width: 100%;
  display: table-cell;
  vertical-align: middle;
}
.main {
  -moz-border-radius: 6px / 6px;
  -webkit-border-radius: 6px 6px;
  border-radius: 6px / 6px;
  padding: 20px;
  background: #4694e8;
  width:300px;
  margin: auto;
  transition: 0.3s;
}
/* When height is 400 or less scale the content to 0.7 */
@media screen and (max-height: 400px) {  
  body {
    background: #444;
  }
  .main {
    -ms-transform: scale(0.7, 0.7);
    -webkit-transform: scale(0.7, 0.7);
    transform: scale(0.7, 0.7);
  }
}
/* When height is 500 or more scale the content to 1.3 */
@media screen and (min-height: 500px) {  
  body {
    background: #222222;
  }
  .main {
    -ms-transform: scale(1.3, 1.3);
    -webkit-transform: scale(1.3, 1.3);
    transform: scale(1.3, 1.3);
  }
}
I recomend also center the content with display:table in html and body tags and display: table-cell with vertical-align: middle in the wrapper div
Here is a demo: https://jsfiddle.net/da2ds0nj/2/
I hope this help you, and excuse me by my english.