Cách thêm CSS Dropdown menu dơn giản cho blogspot:

<style>nav.drop-menu {
  position:relative;
  padding:10px 15px;
  background:transparent;
  width:200px;
  font:bold 16px Arial,Sans-Serif;
  text-transform:uppercase;
  color:#0000ff;
}

nav.drop-menu:after {
  content:"";
  width:0px;
  height:0px;
  border:5px solid transparent;
  border-top-color:#38761d;
  position:absolute;
  top:16px;
  right:14px;
}

nav.drop-menu ul {
  position:absolute;
  top:100%;
  left:0px;
  z-index:99;
  text-transform:none;
  margin:0px;
  padding:0px;
  background:transparent;
  width:100%;
  font-weight:normal;
  display:none;
}

nav.drop-menu li {
  list-style:none;
  margin:0px;
  padding:0px;
}

nav.drop-menu li a {
  display:block;
  margin:0px;
  padding:7px 15px;
  text-decoration:none;
  color:#38761d;
}

nav.drop-menu li a:hover {
  background:#93c47d;
  padding-left:19px;
}

nav.drop-menu:hover ul {
  display:block;
}</style>
<nav class='drop-menu'>
Drop Down Menu
    <ul>
        <li><a href='#'>Home</a></li>
        <li><a href='#'>About</a></li>
        <li><a href='#'>Portfolio</a></li>
        <li><a href='#'>Contact</a></li>
        <li><a href='#'>Archive</a></li>
        <li><a href='#'>Search</a></li>
        <li><a href='#'>Company</a></li>
    </ul>
</nav>