"

From 2012.igem.org

.nav, .nav ul {

 margin:0;
 padding:0;
 list-style:none;
 line-height:1;
 z-index:3

}

.nav {

 display:block;
 position:relative;
 width:1000px;
 height:43px;
 border-bottom:3px solid #fff;
 border-top-left-radius:3px;
 border-top-right-radius:3px;

 background: #494949; /* Background for Internet Explorer 9 and older browsers */
 background: -webkit-linear-gradient(bottom, #444, #555); /* Background for Chrome & Safari */
 background: -moz-linear-gradient(bottom, #444, #555); /* Background for Firefox */
 background: -o-linear-gradient(bottom, #444, #555); /* Background for Opera */
 background: -ms-linear-gradient(bottom, #444, #555); /* Background for Internet Explore 10+ */

}

/* The link containers */

.nav>li {

 display:block;
 float:left;
 position:relative;
 margin:0;
 padding:0;

}

/* The main navigation links */ .nav>li>a {

 /* Layout & positioning */

 display:block;
 width:198px;
 padding:11px 0px;
 border-right:1px dotted #393939;
 border-left:1px dotted #595959;

 /* Typography */

 font-family:Helvetica, Arial, sans-serif;
 font-size:14px;
 font-weight:normal;
 text-decoration: none;
 color:#fff;
 text-shadow:0 1px 0 #2a2a2a;
 text-align:center;

 /* Changing the background on hover with a smooth transition */

 -webkit-transition:background .35s linear;
 -moz-transition:background .35s linear;
 -ms-transition:background .35s linear;
 -o-transition:background .35s linear;
 transition:background .35s linear;

}

/* Changing the background on hover */

.nav>li>a:hover, .nav>li:hover>a { background: rgba(0, 0, 0, .15); background: #414141; }

.nav>li:first-child a { border-top-left-radius: 3px; }

/* The pointer arrow */ .arrow { cursor: pointer;

   height: 0px;
   border: 3px solid transparent;
   border-bottom-color: #fff;
   left: 100px;
   position: absolute;
   bottom: 0px;
   width: 0;
   z-index: 5;

   -moz-transition: all .3s ease;
   -ms-transition: all .3s ease;
   -o-transition: all .3s ease;
   -webkit-transition: all .3s ease;
   transition: all .3s ease;

}

.arrow:hover {

   -moz-transition-duration: 3000s;
   -ms-transition-duration: 3000s;
   -o-transition-duration: 3000s;
   -webkit-transition-duration: 3000s;
   transition-duration: 3000s;

}

.nav li:nth-child(1):hover ~ .arrow, .nav .active:nth-child(1) ~ .arrow {

   left: 100px;

} .nav li:nth-child(2):hover ~ .arrow, .nav .active:nth-child(2) ~ .arrow {

   left: 300px;

} .nav li:nth-child(3):hover ~ .arrow, .nav .active:nth-child(3) ~ .arrow {

   left: 500px;

} .nav li:nth-child(4):hover ~ .arrow, .nav .active:nth-child(4) ~ .arrow {

   left: 700px;

} .nav li:nth-child(5):hover ~ .arrow, .nav .active:nth-child(5) ~ .arrow {

   left: 900px;

}

/* General styling for the submenus */ .nav ul { display: block; position: absolute; left: -9999px; text-align: center; box-shadow: 0 1px 2px rgba(0, 0, 0, .15); }

/* Level 1 submenus */ .nav>li>ul { cursor: pointer; padding-top: 0px; z-index: 200; top: 43px;

}

/* Making the level 1 submenu to appear on hover */ .nav>li:hover>ul { left: -1px; }

/* The submenu link containers */ .nav ul li { position: relative; display: block;

/* Creating the slide effect. The list elements which contain the links have 0 height. On hover, they will expand */ height: 0px; -webkit-transition: height .2s; -moz-transition: height .2s; -o-transition: height .2s; -ms-transition: height .2s; }

/* Expanding the list elements which contain the links */ .nav li:hover>ul>li { height: 24px; }

.nav>li:hover>ul>li:first-child { height: 27px; }

.nav>li>ul>li:first-child>a { border-top: 3px solid #fff; }

.nav>li>ul>li.dropdown:first-child>ul { top: 3px; }

/* The links of the submenus */ .nav ul li a { /* Layout */ display: block; width: 171px; padding: 6px 10px 6px 20px;

/* Typography */ font-size: 12px; color: #999; font-family: Helvetica, Arial, sans-serif; text-decoration: none; background: #f0f0f0;

/* Every change to the links (background, color etc) will be made with a smooth transition */ -webkit-transition: all .2s; -moz-transition: all .2s; -ms-transition: all .2s; -o-transition: all .2s; transition: all .2s; }

.nav>li>ul>li:first-child>a::before { content: ""; display: block; position: absolute; text-align: center; width: 100%; height: 6px; background: transparent; top: -6px; left: 0; z-index: 9999; }

/* The hover state of the links */ .nav ul li:hover>a, .nav ul li>a:hover { background: #e7e7e7; color: #f2c100; }

/* Changing the color of the arrow on hover */ .nav ul>.dropdown:hover>a::after, .nav ul>.dropdown>a:hover::after { border-left-color: #f2c100; }