Z-索引不工作，使div包含下拉菜單重疊導航

我目前正在建設一個網站，真的很喜歡我的「4位置」下拉菜單工作。但導航菜單與其重疊。我最初的想法是，我們Z-index將它堆疊在主導航之上，但它不起作用。我能做什麼？？查看它：去http://pcfm.adamerica.me/Z-索引不工作，使div包含下拉菜單重疊導航

這是CSS：

/* Dropdown Button */ 
.location-dropbtn { 
    background-color: #4CAF50; 
    color: white; 
    padding: 10px; 
    font-size: 12px; 
    border: none; 
    cursor: pointer; 
} 

/* Dropdown button on hover & focus */ 
.location-dropbtn:hover, .location-dropbtn:focus { 
    background-color: #3e8e41; 
} 

/* The container div - needed to position the dropdown content */ 
.location-dropdown { 
    position: absolute; 
    display: inline-block; 
    margin-top: -10px; 
    margin-left: 20px; 
    margin-right: 20px; 
    z-index: 110001; 
} 

/* Dropdown Content (Hidden by Default) */ 
.location-dropdown-content { 
    display: none; 
    position: absolute; 
    background-color: #4CAF50; 
    color: #ffffff; 
    min-width: 160px; 
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2); 
    z-index: 110001; 
} 

/* Links inside the dropdown */ 
.location-dropdown-content a { 
    color: #ffffff; 
    font-size: 12px; 
    padding: 12px 16px; 
    text-decoration: none; 
    display: block; 
    z-index: 110001; 
} 

/* Change color of dropdown links on hover */ 
.location-dropdown-content a:hover { 
    background-color: #3e8e49 
} 

/* Show the dropdown menu */ 
.show { 
    display:block; 
    z-index: 110001; 
}

來源

2017-05-17 Brittany Fleming