Logo/Header space

I’ve tried to add css codes to the css editor (see below) to resize my header space as well as make my logo image fill the width of the white area but cannot get any results. Please help. I am using Sparkle.

#site-title {
margin: 0;
padding: 0;
border: 0;
}
#header {
margin: 0;
padding: 0;
border: 0;
}