#main_menu_master{width: 180px; margin: 0; padding: 0; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 12px; text-align: center; line-height: 30px;}
#main_menu_master a{display: block; color: white; text-decoration: none;}

.top_button a{background: url(image/bt.png); height: 30px; width: 150px; padding: 10px 15px 6px 15px;}
.bot_button a{background: url(image/bb.png); height: 30px; width: 150px; padding: 6px 15px 10px 15px;}
.mid_button a{background: url(image/bm.png); height: 30px; width: 150px; padding: 7px 15px 7px 15px;}

.top_button a:hover{background: url(image/bt.png) bottom;}
.bot_button a:hover{background: url(image/bb.png) bottom;}
.mid_button a:hover{background: url(image/bm.png) bottom;}