Why use percentage value for div's width in CSS?

Question

I am reading articles about css. I found out that many of writers suggest to use % value for div\'s width or height.

I am using pixels all the time.

Why should I

Answer 1

Because if it's percentage based content flows making it easier to implement a responsive site (easier = (less (time = money))).

Drop the relevant floats, sort out your menus and and anything else after dropping in some media queries and you've got a site working on different resolutions and devices.

I use a fluid grid system using percentages and a ems for text sizes. Pixels are easier to work with but not in responsive terms. I do wrap my size in max width container.

PS

Remember though everything boils down to pixels in the end.