If you look in the style.css for that skin you will see it explicitly hides those in the center and alternate panes. You could edit it, but it is done that way on purpose because of the color scheme in the side columns whereas the center is just white. The design was not intended to have round corners anywhere but the side columns.
.altcontent1 .rtop,.altcontent1 .rbottom,.center-leftmargin .rtop,.center-leftmargin .rbottom,.center-rightmargin .rtop,.center-rightmargin .rbottom,.center-nomargins .rtop,.center-nomargins .rbottom,.center-rightandleftmargins .rtop,.center-rightandleftmargins .rbottom,.logolist,.pageicons,.skiplink {
display:none;
}
Hope it helps,
Joe