CSS-Sub菜单在悬停时消失，但显示子子菜单

Question

当我将鼠标悬停在菜单上时会显示子菜单。如果我将鼠标悬停在子菜单上，则会显示子子菜单，但子菜单会消失。 防爆。 test test-1 test-2是菜单，test-2包含3个子菜单，如test-21 test-22 test-23。 test-21包含2个子子菜单，如test-211 test-212。如果我将鼠标悬停在test-2上，则会显示test-21，test-22，test-23。如果我将鼠标悬停在test-21上，则显示test-211，test-212但test-21消失。

Answer 1

试试这个

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@import url(http://fonts.googleapis.com/css?family=Bree+Serif);

h1,p {
	text-align:center;
	font-family: 'Bree Serif', 'serif';
	}

h1 {
	font-size:60px;
}

p {
  font-size:20px;
}

nav { margin:100px auto; width:800px; }

nav ul {
	padding:0;
	margin:0;
	list-style: none;
	position: relative;
	display:block;
	}
	
nav ul li {
	float:left;
	display:list-item;
	list-style: none; 
	
	background-color:#64abfb;
	border-bottom: 5px solid #2ecc71;
	}

nav ul li a {
	display:block;
	padding:15px 10px;	
	
	color:#FFF;
	font-size:20px;
	text-decoration:none;
	font-family: 'Bree Serif', 'serif';
}

li a:hover { background-color: #2ecc71; }

	
/* Change this in order to change the Dropdown symbol */
li > a:after { content: ' »'; } 
li > a:only-child:after { content: ''; }  	
	
	
/* The Dropdown Styles */
/* =================== */

/* Hide Dropdowns by Default */
nav ul ul {
	display: none;
	position: absolute; top: 58px;
}
	
/* Display Dropdowns on Hover */
nav ul li:hover > ul {
	display:list-item;
}
	
/* Fisrt Tier Dropdown */
nav ul ul li {
	width:170px;
	float:none;
	position: relative;
	border-bottom:none;
}

/* Second, Third and more Tiers	*/
nav ul ul ul li {
	position: absolute relative;
	top:-58px; 
	left:170px;
}

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<p>Dropdowns are marked with " » "<br/>
</p>
<nav>
    <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">WordPress</a>
        <!-- First Tier Drop Down -->
        <ul>
            <li><a href="#">Themes</a></li>
            <li><a href="#">Plugins</a></li>
            <li><a href="#">Tutorials</a></li>
        </ul>        
        </li>
        <li><a href="#">Web Design</a>
        <!-- First Tier Drop Down -->
        <ul>
            <li><a href="#">Resources</a></li>
            <li><a href="#">Links</a></li>
            <li><a href="#">Tutorials</a>
        	<!-- Second Tier Drop Down -->
            <ul>
                <li><a href="#">HTML/CSS</a></li>
                <li><a href="#">jQuery</a></li>
                <li><a href="#">Other</a></li>
            </ul>
            </li>
        </ul>
        </li>
        <li><a href="#">Graphic Design</a></li>
        <li><a href="#">Inspiration</a></li>
        <li><a href="#">Contact</a></li>
        <li><a href="#">About</a></li>
    </ul>
</nav>

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