Question

I’m starting off a new web project and I’m wondering whether to use em or px for the layout and font sizes.

Despite the fact that most browsers now support text and image zooming regardless of whether fonts are defined in px or em, the community support for using em is still strong.

But there are 2 problems I see with using em.

First is the problem with large and wide monitors – often this results in text running miles and miles across the screen, which is very difficult to read as you read down the page.

Secondly, what if your site needed to integrate a Flash component? If you want the Flash component to fit exactly inside a div (e.g the main container of the site) that is defined in em, how would you go about it since Flash components are measured in px?

Is there a compelling reason to use EM over PX, really?

Answer 1

First is the problem with large and
wide monitors – often this results in
text running miles and miles across
the screen, which is very difficult to
read as you read down the page.

Using em or px, you can still define a width (or max-width) to your layout.

Secondly, what if your site needed to
integrate a Flash component? If you
want the Flash component to fit
exactly inside a div (e.g the main
container of the site) that is defined
in em, how would you go about it since
Flash components are measured in px?

To fit exactly, you can still use 100% width, or maybe I did not understand your point.

---

In theory, using em instead of px will allow your layout to be easily sizable based on user preferences.

But today, modern browsers can resize px layouts as well as em layouts so it might not be as relevant as it was some years ago.