怎么把菜单放在顶部横着呀，这个只能在左侧

.menu {
font-family: arial, verdana, sans-serif;
position: relative;
}
.rb_toggle {
height: 25px;
line-height: 25px;
padding: 0 5px 0 0;
}
.rb_toggle span {
color: #999;
font-size: 11px;
font-weight: bold;
font-family: arial, verdana, sans-serif;
cursor: hand;
cursor: pointer;
}
.rb_toggle span.hover {
color: red;
}
.rb_menu {
position: absolute;
left: 50px;
top: 0;
}
.rb_menu ul, .rb_menu li {
list-style-type: none;
padding: 0;
margin: 0;
}
.rb_menu li {
float: left;
width:160px;
height: 25px;
padding: 0 10px 0 0;
}
.rb_menu a {
font-size: 16px;
font-weight: regular;
color: #f90;
text-decoration: none;
}
.rb_menu a:hover {
text-decoration: underline;
}
.rb_menu a.current {
color: #999;
}
.clearfix:after {
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;
}
.clearfix {
display: inline-block;
}
/* Hides from IE-mac */

• html .clearfix {
  height: 1%;
  }
  .clearfix {
  display: block;
  }

rb_menu加个100%的宽度