CSS规则，如果内容不适合，则切换内容-CSSrulestoswitchcontentifitdoesnotfit

.table-row{
    display: table-row;
}
.table-cell{
    display: table-cell;
    vertical-align: middle;
    white-space: nowrap;
}

.wrapper{
   height:75px; /*the height of your menu, it's critical to define this value equal to the horizontal menu height*/
   overflow:hidden; /*this will hide the horizontal menu when the screen width is too small*/
}

.top_nav{
   padding-right:120px; /*allow space for right section*/
   background-color: green;
   color:white;
}
.top_nav_background{ /* this serves as a background for the rest of the structure, pay attention if you have other z-indexed elements */
   background-color:green; 
   height:85px; 
   width:100%; 
   position:absolute; 
   top:0px; 
   z-index:-1;
}
.floating-box {
    height: 55px;
    padding:10px;
    float: left;
    border: 1px solid #73AD21;
    background-color:green;
}
.h-menu{
    height: 75px;
    float: left;
    min-width: 150px;
    background-color:yellow;
}
.h-menu-item{
   height: 55px;
   padding:10px;
   border: 1px solid #73AD21;
}
.v-menu{
    margin-top:20px;
    height: 20px;
    background-color:red;
}
.right-items{
   position:absolute; 
   right:20px; 
   top:20px; 
   color:white;
}

  
   


     
Left section.

     

        
item1
        
item2
        
item3
        
long long long item4
     
     
v-menu
     
   
   
   
Right section.