Why can't I edit the code?

I'm very new to ckeditor and I want to edit html code by myself.

When I write "something" in ckeditor and switch to code view, I see

<p>something</p>

that's all right. but I want to edit code like:

<p style="color: #fff; font-size: 73px;">something</p>

when I do this and return to WYSIWYG, nothing changes. when I switch to code view again, I get

<p>something</p>

again.

How can I prevent that? I want to write and edit the code by myself too.

Second question. A few months ago, I've tried ckeditor and every time I want to post, my server blocked me with "403 forbidden". Some people said it might be related to "mod_security". When I disable it, ckeditor worked fine. Is there any other way to not get 403 error?