Css frameworks have become hugely popular. There are few developers that haven't heard to Bootstrap CSS framework, which can elegantly handle tablets and mobile devices, without a need for horizontal scroll.
Not many might know that Bootstrap was started by a few of Twitter developers, and was used by Twitter.
However, recently, twitter moved to another framework, SuitCSS. It's main advantage is that this framework is light-weight compared to Bootstrap, and you can extend it with separate components. This way, you get to use only what you need, loading fewer styles on the client.
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