What are the default margins for the html heading tags (<h1>, <h2>, <h3>, etc.)?

Question

I avoid using the defaults with the reset code below:

margin:0px; and padding:0px;

For example, what are the default margins for the heading tag below?

<h1>Header</h1>

Answer 1

It's different regarding which browser, thus if you want a pixel-perfect design then practice is to "reset" those values to 0 (margin and padding) and set them yourself.

"CSS reset" is very common to front-end developers, a simple example of one i use :

html,body,blockquote,code,h1,h2,h3,h4,h5,h6,p,pre{margin:0;padding:0}
button,fieldset,form,input,legend,textarea,select{margin:0;padding:0}
fieldset{border:0}
a,a *{cursor:pointer}
div{margin:0;padding:0;background-color:transparent;text-align:left}
hr,img{border:0}
applet,iframe,object{border:0;margin:0;padding:0}
button,input[type=button],input[type=image],input[type=reset],input[type=submit],label{cursor:pointer;}
ul,li{list-style:none;margin:0;padding:0;}
strong{font-weight:bold;}
em{font-style:italic;} 

Answer 2

Your Question:

It varies between browsers. Check each browser's specific default stylesheets to tell.

For Google Chrome for example, it's 0.67em.

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A Better Solution?

Do know that if you wish to aim for x-browser consistency, you'll have to use a CSS Reset.

The most common one being:

* { padding: 0; margin: 0; }

Although other (and probably better) exist.

Answer 3

The CSS specification has an informative Appendix D. Default style sheet for HTML 4.

Although it is informative it still says:

Developers are encouraged to use it as a default style sheet in their implementations.

There you can find

h1              { font-size: 2em; margin: .67em 0 }
h2              { font-size: 1.5em; margin: .75em 0 }
h3              { font-size: 1.17em; margin: .83em 0 }
h4, p,
blockquote, ul,
fieldset, form,
ol, dl, dir,
menu            { margin: 1.12em 0 }
h5              { font-size: .83em; margin: 1.5em 0 }
h6              { font-size: .75em; margin: 1.67em 0 }