div.corner {
    position: relative;
}

span.corner {
    position: absolute;
    height: 12px;
    width: 12px;
    display: block;
}

.corner_white_top_left {
    background: transparent url('images/corner_top_left_white.png') no-repeat left top;
    top: 0;
    left: 0;
}

.corner_white_top_right {
    background: transparent url('images/corner_top_right_white.png') no-repeat left top;
    top: 0;
    right: 0;
}

.corner_white_bottom_left {
    background: transparent url('images/corner_bottom_left_white.png') no-repeat left bottom;
    bottom: 0;
    left: 0;
}

.corner_white_bottom_right {
    background: transparent url('images/corner_bottom_right_white.png') no-repeat left bottom;
    bottom: 0;
    right: 0;
 }

.corner_grey10pc_top_left {
    background: transparent url('images/corner_top_left_grey10pc.png') no-repeat left top;
    top: 0;
    left: 0;
}

.corner_grey10pc_top_right {
    background: transparent url('images/corner_top_right_grey10pc.png') no-repeat left top;
    top: 0;
    right: 0;
}

.corner_grey10pc_bottom_left {
    background: transparent url('images/corner_bottom_left_grey10pc.png') no-repeat left bottom;
    bottom: 0;
    left: 0;
}

.corner_grey10pc_bottom_right {
    background: transparent url('images/corner_bottom_right_grey10pc.png') no-repeat left bottom;
    bottom: 0;
    right: 0;
}