my header is too big!!!

hello, I’m having huge problems with my wordpress header. I am using the thirty ten theme (a basic mod of the twenty then that adds an extra column. It seems if I edit the stylesheet from twenty ten this makes changes to the themes header. My header too much white space between my header image and top of the page. Below is my stylesheet code. I have tried padding in the branding part of the code. It moves the image down further if I use a positive number. But it won’t move the image up using a negative number. Why is this? In my site description I use this : margin: -70px 0 18px -100px; and the -70px moves the description up. So I want to do a similar thing with my header image. I just want to move it up! How do I do this please? My stylesheet code is below:

#header {
padding: -100px 0 0 0;
}
/* Default padding is 30*/

#site-title {
float: left;
font-size: 15px;
line-height: 36px;
margin: 0 0 18px 0;
width: 700px;
text-indent: -999em; /*hide the title*/

}
#site-title a {
color: #000;
font-weight: bold;
text-decoration: none;

}
#site-description {
clear: right;
float: right;
font-style: italic;
font-size: 20px;
margin: -70px 0 18px -100px;
width: 400px;
}

* This is the custom header image */
#branding img {

clear: both;
display: block;
padding:-100px 0 1px;/*trying to move image up with -100*/

}