When to style directly in the HTML instead of CSS

Question

I've tried to search for a subject on this, but I haven't found any, so I thought I'd go ahead.

My question is when it is correct, if anytime, to just put your style directly in your HTML file, instead of using a .css file.

I mean, I get that it is very useful to use your .css file when you have alot of things that needs to be repeated, or is used on several pages. But in my case, I have one page where I'm about to style something, that I'm pretty sure only will be on that page. This being the width, height, and small stuff for a div.

To show you what I mean, here's the code:

<div style="margin:0px auto; width:600px;">
    <div style="float:left">
        <p class="InputFieldsText">Brugernavn</p>
        <div class="InputFields"><input name="Text1" type="text" class="Medium" placeholder="Din e-mail adresse" /></div>
        <p class="InputFieldsUnderText"><a href="#">Glemt dit brugernavn?</a></p>

        <p class="InputFieldsText">Password</p>
        <div class="InputFields"><input name="Text1" type="password" class="Medium" /></div>
        <p class="InputFieldsUnderText"><a href="#">Glemt dit password?</a></p>

        <input onclick="window.location='user_page.html'" class="LargeIndent" name="Submit1" type="button" value="Log ind" />
    </div>
    <div style="float:left; width:172px; text-align:center">            
        <img alt="" height="128" src="images/lock.png" width="128">
    </div>
</div>

So, as you can see, in some divs I styled it directly, instead of coming up with a name for my class and put on there. I know it isn't wrong to do, since it will come out the same if I used it in my .css file and called a class, but is there a "guideline" or something that this and this is not recommended etc. etc.

Hope you understood my question. Really not that big of a deal, I've just always wondered :)

Regards

Answer 1

The answer is pretty simple, IMO: never. :)

You should always use a style sheet, because it allows you to quickly and easily change the entire appearance and layout of your site. If you embed the style information in the HTML directly, you have to work a lot harder if something needs to change; with a style sheet, you simply change the CSS file in a single location, and the change becomes global everywhere that style sheet is used.