if you mean the margin/padding over the h block, that would come from browser's default css rules and may differ from one browser to another, if you want to make sure every browser display stuff as close as possible to what you would like (it's impossible to have EXACTLY the same thing on everybrowser since they handle css diferently to their liking) what i would suggest is importing a reset.css set of rules that clears the browsers default values for generic elements.
the order for css rules is : broswer's css < website's css file/style elements < inline style arguments < user's personal css
im probly missing some here but the important point i'm trying to make is that your website's css is rarely gonna overwrite every single possibile rules that the browser possibly implements, this is where the reset.css comes into play and wipes as much as possible off by setting default values for elements that could otherwise be implemented diferently by diferent browsers...
so you end up with : broswer's css < reset.css < website's css file/style elements < inline style arguments < user's personal css
here is the reset.css i found a bit ago on the net and use currently :
edit : when i talk about css rule's order i do not mean the weight, that still takes over the order the diferent files are loaded.
html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed,
figure, figcaption, footer, header, hgroup,
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
margin: 0;
padding: 0;
border: 0;
font-size: 100%;
font: inherit;
vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure,
footer, header, hgroup, menu, nav, section {
display: block;
}
body {
line-height: 1;
}
ol, ul {
list-style: none;
}
blockquote, q {
quotes: none;
}
blockquote:before, blockquote:after,
q:before, q:after {
content: '';
content: none;
}
table {
border-collapse: collapse;
border-spacing: 0;
}