HTML / CSS - adjust font-size to fill parent height and width

Question

I have a <div> element that resizes as the browser window resizes.

Inside the <div> I have a paragraph of text:

<div style="width:80%; height:80%; margin:10%;">
    <p>Paragraph of text. Paragraph of text. Paragraph of text.</p>
</div>

I want the text to change font-size as I resize the <div>, so that the text will occuypy 100% of the available space.

How can I achieve this effect?
Would it be with a percentage font-size?
Would I have to use Javascript?

Thanks in advance!

Answer 1

There's a jquery plugin for this: http://fittextjs.com/

Answer 2

HTML

<div id="change" style="margin:10%;"> 
    <p>Paragraph of text. Paragraph of text. Paragraph of text.</p> 
</div> 

CSS

#change { 
    width: 80%; 
    height: 80%; 
    border: 1px solid black; 
    overflow: hidden; 
    font-size: 1em; 
} 

JAVASCRIPT

$(function() { 
    while( $('#change div').height() > $('#change').height() ) { 
        $('#change div').css('font-size', (parseInt($('#change div').css('font-size')) - 1) + "px" ); 
    } 
}); 

Answer 3

What you need is called vw. Example CSS: font-size: 80vw;. vw means viewerport width, and 80vw = 80% of the device screen width