.main { width:100%;}
.min_width {width:expression(((document.documentElement.clientWidth || document.body.clientWidth) < 780)? "780px" : "100%"); min-width:780px;}


.col_1, .col_2, .col_3, .col_box_1, .col_box_2, .f_l{ float:left;}
.f_r { float:right;}

.content .col_1{width:280px;}
.content .col_2{width:500px;}