Val Head, writing for Typecast:
[CSS max-width] is your best buddy in fluid design. It allows an element to scale down as screen sizes decrease, but at the same time lets you control when bigger is just too big. An element will widen to the limit you set, and when the browser widens beyond that point, the margins to the left and right will expand to fill the space around it.
Balancing typographic sensitivity (like acceptable line lengths) with fluidity (in response to diverse screen sizes) is an important part of web design, and CSS
max-width can help.