Навигационное меню на CSS3

<nav>
  <ul>
  <li><a href="">Главная</a></li>
  <li><a href="">Категории</a></li>
  <li><a href="">О нас</a></li>  
  <li><a href="">Портфолио</a></li>
  <li><a href="">Контакт</a></li>
  </ul>
</nav>

nav {
  display: block;
  width: 100%;
  overflow: hidden;
}

nav ul {
  margin: 80px 0 20px 0;
  padding: .7em;
  float: left;
  list-style: none;
  background: #444;
  background: rgba(0,0,0,.2);
  -moz-border-radius: .5em;
  -webkit-border-radius: .5em;
  border-radius: .5em;  
  -moz-box-shadow: 0 1px 0 rgba(255,255,255,.2), 0 2px 1px rgba(0,0,0,.8) inset;
  -webkit-box-shadow: 0 1px 0 rgba(255,255,255,.2), 0 2px 1px rgba(0,0,0,.8) inset;
  box-shadow: 0 1px 0 rgba(255,255,255,.2), 0 2px 1px rgba(0,0,0,.8) inset;  
}

nav li {
  float:left;
}

nav a {
  float:left;
  padding: .8em 1.5em;
  text-decoration: none;
  color: #555;
  text-shadow: 0 1px 0 rgba(255,255,255,.5);
  font: bold 1.1em/1 'trebuchet MS', Arial, Helvetica;
  letter-spacing: 1px;
  text-transform: uppercase;
  border-width: 1px;
  border-style: solid;
  border-color: #fff #ccc #999 #eee;
  background: #c1c1c1;
  background: -moz-linear-gradient(#f5f5f5, #c1c1c1);
  background: -webkit-gradient(linear, left top, left bottom, from(#f5f5f5), to(#c1c1c1));
  background: -webkit-linear-gradient(#f5f5f5, #c1c1c1);
  background: -o-linear-gradient(#f5f5f5, #c1c1c1);
  background: -ms-linear-gradient(#f5f5f5, #c1c1c1);
  background: linear-gradient(#f5f5f5, #c1c1c1);  
  }
   
nav a:hover, nav a:focus {
  outline: 0;
  color: #fff;
  text-shadow: 0 1px 0 rgba(0,0,0,.2);
  background: #fac754;
  background: -moz-linear-gradient(#fac754, #f8ac00);
  background: -webkit-gradient(linear, left top, left bottom, from(#fac754), to(#f8ac00));
  background: -webkit-linear-gradient(#fac754, #f8ac00);
  background: -o-linear-gradient(#fac754, #f8ac00);
  background: -ms-linear-gradient(#fac754, #f8ac00);
  background: linear-gradient(#fac754, #f8ac00);
}

nav a:active {
  -moz-box-shadow: 0 0 2px 2px rgba(0,0,0,.3) inset;
  -webkit-box-shadow: 0 0 2px 2px rgba(0,0,0,.3) inset;
  box-shadow: 0 0 2px 2px rgba(0,0,0,.3) inset;
}
   
nav li:first-child a {
  border-left: 0;
  -moz-border-radius: 4px 0 0 4px;
  -webkit-border-radius: 4px 0 0 4px;
  border-radius: 4px 0 0 4px;  
}

nav li:last-child a {
  border-right: 0;
  -moz-border-radius: 0 4px 4px 0;
  -webkit-border-radius: 0 4px 4px 0;
  border-radius: 0 4px 4px 0;  
}