Center Div with aspect Ratio

Question

I need to Center a Div in the html viewport. It should be centered both, vertically and horizontally. But the Div should keep its aspect ratio (4/3) and have a minimum margin of 10px.

I made a Javascript:

function resizeWindow() {
 var wHeight = $(document).height() - 20;
 var wWidth = $(document).width() - 20;
 var gameStage = $("#gameStage");
 if ((wWidth / 4) * 3 <= wHeight) {
  gameStage.css("width", wWidth + "px");
  gameStage.css("height", ((wWidth / 4) * 3) + "px");
  gameStage.css("top", (wHeight - ((wWidth / 4) * 3)) / 2 + 9 + "px");
  gameStage.css("left", "10px");
 } else {
  gameStage.css("height", wHeight + "px");
  gameStage.css("width", ((wHeight / 3) * 4) + "px");
  gameStage.css("left", (wWidth - ((wHeight / 3) * 4)) / 2 + 9 + "px");
  gameStage.css("top", "10px");
 }
}

https://jsfiddle.net/3sw06kvb/

But User, who disabled Javascript will not be able to use my website. And a solution with HTML/CSS should be faster(?).

My first Idea is to make a wrapper with

position: fixed 
top, left, bottom, right = 20px;.

But my problem is making a div centering vertically and horizontally while keeping its aspect ratio.

https://jsfiddle.net/xep2mf62/

Answer 1

You can try the following in the CSS. The new units in CSS3 vh and vw allows you to set the height depending on the size of the viewport. height:100vh will give the element a height that is equal to the height of the browser window.

***1vw = 1% of viewport width

1vh = 1% of viewport height***

    .wrapper {
      position: relative;
      width:100%;
      height:100vh;
    }
    .childdivision {
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      height:50vw;
       width:90vw;
      border:2px solid #444;
    }

<div class="wrapper">
  <div class="childdivision">
    </div>
  </div>