Adding class to header on each category

[Elfiszcze]

Hello.

I need to add class to header for each category.

In header.tpl of my template I have 

<header id="header">

I need to have something like this:

<header id="header" class="category-id-3">

How can I achive that?

 

[Elfiszcze]

I figured it out.

 

It shoud be:

<header id="header" {if $smarty.get.id_category} class="category_{$smarty.get.id_category}"{/if}>

code will look like this:

<header id="header" class="category_3>

Edited June 9, 2015 by Elfiszcze (see edit history)

[ventura]

 it is not necessary add a smarty variable. Only with css 

.cat-3 #header