[totaltec]

Are you trying to change the size of the header?

For the default skin:
In main.css these are the settings that control the header:
#content-container {
margin-top: 193px;
}
#header {
height: 193px;
}

Additionally you should change the checkout containers height depending on your style of checkout, Fast lane or OPC.

Since you are using Vivid Dreams Lotus look at these in altskin.css:
#content-container {
margin-top: 287px;
}
#header {
height: 287px;
}
#header .head-bg2 {
height: 287px;
}
.cart-block {
height: 239px;


}

Again you are going to need to look for different styles to apply during checkout. Let me know if you need more info.