CodePen

HTML

            
              <nav>
  <ul>
    <li>
    <a href="#" data-caption="Home">Home</a>
  </li> 
  <li class="list-item--active">
  <a href="#" class="active" data-caption="About">About</a>
  </li> 
  <li>      
  <a href="#" data-caption="Images">Images</a>
  </li> 
  <li>      
  <a href="#" data-caption="Videos">Videos</a>
  </li> 
  <li>      
  <a href="#" data-caption="Contact">Contact</a>
  </li> 
  </ul>
</nav> 
            
          
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↑ Insert the most common viewport meta tag

CSS

            
              * { 
  margin:  0;
  padding:  0;
  border:  0;
  vertical-align:  baseline; 
  /* outline: 1px dotted salmon; */
}
a {
  text-decoration:  none;
}
nav {
  font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; 
  display:  block; 
  height: 40px;
  background-color: #E8E8E8;
  padding: 1px 0;
}
nav ul {
  list-style: inside none;
}
nav li {
  float: left; 
  height: 40px;
  width: 90px;
  overflow: hidden;
  text-align: center;
  text-transform: uppercase; 
  margin-right: 1px; /* keep 1px between elements */
  position: relative;
}
.list-item--active {
  overflow: visible; 
}
nav a { 
  width: 100%;
  font-size: 12px; 
  color: #333;
  /* position: absolute; */
  /* top: 0; left: 0; right: 0; */
  position: relative;
  display: block;
  line-height: 40px; /* Vertically center text by making line height equal to height */
  /* Transitions effects for all browsers */
  -webkit-transition: all 200ms ease-in; /* Old webkit version including chrome, safari, etc. */
  -moz-transition: all 200ms ease-in; /* Old Firefox version */
  -ms-transition: all 200ms ease-in; /* IE 10+ - IE < 10 will just apply the top position without any transition affect */
  -o-transition: all 200ms ease-in; /* Old opera support */
  transition: all 200ms ease-in; /* Normal declatration */
}
nav a:hover
/*, nav a.active */ { 
  top: -100%;
}
/* http://css-tricks.com/pointer-events-current-nav/ */
nav a.active {  
  top: 0;
  pointer-events: none;
  cursor: default;
  background-color: #6495ED;
  color: #fff;
}
nav a.active:after {
  content: "";
  width: 0; 
  height: 0;
  position: absolute;
  top: 40px;
  left: 33.33%;
  width: 0;
  height: 0;
  border-left: 15px solid transparent;
  border-right: 15px solid transparent;
  border-top: 10px solid #6495ED;
  background-color: transparent;
}
/* Insteed of badly duplicating text content in a span, use :after pseudo class add a blue block after the element with all required attributes. see pseudo class :after and :before for more details */
nav a:after {
  content: attr(data-caption); /* Use the data-caption attribute for the text content */
  display: block; 
  position: absolute;
  top: 100%;
  width: 100%; 
  height: 40px;
  background-color: #6495ED;
  color: #fff;
}
            
          
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JS

            
              // demo to answer a question in the css-tricks forums: http://css-tricks.com/forums/discussion/24987/active-page-navigation-triangle-help-
// it's a fork of: http://jsfiddle.net/attilahajzer/6Sxak/10/
            
          
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