How are these two sites built to be 'responsive'?

I am looking into responsive web design and have come across many methods of doing so, however I am struggling to distinguish the best method of doing so.

I -really- like the how these two sites work:

1. http://paulrobertlloyd.com/
2. http://colly.com/

However I cannot seem to figure out how the are dynamically changing their layouts. Is there a technique I am missing that is not listed below?

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So far I have come across the following methods:

1: Javascript

Example - adapt.js

Detects the screen resolution dynamical开发者_StackOverflow社区ly and selects the appropriate stylesheet.

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2: CSS3 Media queries

Using a technique like:

@media only screen and (max-width: 480px) and (min-width: 320px) {

}

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3: Backend

Example - Prepending PHP files

Only really works for a single mobile version of a site, mirroring the original domain and changing the headers.

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Both of those websites use media queries, as you can see in the bottoms of their respective CSS files.

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This is generally referred to as elastic CSS.

There is a framework for it here: http://elasticss.com/ I should say though that I have never used it personally, so there might be something better.