.: 2011

Use this code. I'll assure you it will work

/* decrease gap */

#sidebar-left-1 {
margin-right:-2px;
}

.column-right-inner {
margin-left:-15px;
}

/* end of decrease gap */

/* center header */

#header-inner img {
display:block;
margin-right:auto;
margin-left:auto;
}

/* end of center header */

/* decrease space under header */

.tabs-outer {
margin-bottom:-2px;
}

/* end of decrease space under header */

.sidebar .widget {margin: 5px 0;}

Change #px in a manner that will suits your need