For some reason, FCKEditor automatically wraps any content entered into the textbox with a <p> tag. This can cause for some problems in your layout when you’re actually displaying the content. Instead of trying to fix this in your layout with CSS, there is a quick and easy way to turn the auto-wrap off in FCKEditor: Change the FCKConfig.EnterMode setting from ‘p’ to ‘br’. There are a few ways to handle this:

• Edit fckconfig.js:
  Change FCKConfig.EnterMode = 'p'; to FCKConfig.EnterMode = 'br';
• Change the setting programatically when you instantiate the object, like so (in PHP):
  <?php
include_once('fckeditor/fckeditor.php');
$oFCKeditor = new FCKeditor('description');
$oFCKeditor->BasePath = '/fckeditor/';
$oFCKeditor->Value = 'some text';
$oFCKeditor->Config['EnterMode'] = 'br'; // turn off auto <p> tags wrapping content
$oFCKeditor->Create();
?>

I prefer the latter way because you can do it on a page by page basis, and there’s no messing with FCK’s core JavaScript files.