.s1 {  font-size: 12px; line-height: 18px}
.s2 {  font-size: 14px; line-height: 19px}
.s3 {  font-size: 16px; line-height: 20px}
.back_of {  background-attachment: scroll; background-image: url(images/office/image2.jpg); background-repeat: no-repeat; background-position: 300px center}
.back_to {  background-attachment: scroll; background-image: url(images/top/image2.jpg); background-repeat: no-repeat; background-position: 350px 50px}
.toptxt {  font-size: 13px; line-height: 19px}
.back_top { background-attachment: scroll; background-image: url(images/top/image6.jpg); background-repeat: no-repeat}