Complementing Erik's great suggestion...
I love Ethan Marcotte's book
Responsive Web Design.
Ethan coined that term and design principles in
May 2010 and remains the leading reference.
As a side note, responsive websites are built on a fluid grid and use media queries to control the design and its content as it scales down or up with the browser or device. In few words, responsive is the natural evolution.
.png)