CSS 'length' property info please?

Hi.

In a site I have set the height of a footer div to 4em. This doesn't
validate, therefore I *assume* that em is not a valid value. I will
change it, of course, but I want to learn the correct possible values.

Sorry! We found the following errors
URI : http://www.thermachek.com/temp/thermachekv2.css
181 #footer Value Error : height Parse Error - 4em

OK, so I went to http://www.w3schools.com/css/css_reference.asp to
read up. Under height is says the possible values are auto, length or
%.

So whats the definition of 'length'? Searching the site has brought up
nothing, so far. It must be there, but I can't find it. Can anyone
point out the px in what % of the site for em?

Thanks.

On 2008-03-02, Mike Barnard <m.barnard.trousers (AT) thunderin (DOT) co.uk> wrote:

Hi.

In a site I have set the height of a footer div to 4em. This doesn't
validate, therefore I *assume* that em is not a valid value. I will
change it, of course, but I want to learn the correct possible values.

Sorry! We found the following errors
URI : http://www.thermachek.com/temp/thermachekv2.css
181 #footer Value Error : height Parse Error - 4em

You forgot the :. You wrote 'height 4em', not 'height: 4em'.

OK, so I went to http://www.w3schools.com/css/css_reference.asp to
read up. Under height is says the possible values are auto, length or
%.

So whats the definition of 'length'? Searching the site has brought up
nothing, so far. It must be there, but I can't find it. Can anyone
point out the px in what % of the site for em?

An em is a perfectly good length unit, you jumped the wrong way.

Validators etc. can give slightly misleading error messages because
after all they're only non-human.

The main useful information is just "there's something wrong near line
181". Everything else take with a pinch of salt.