How to change the color of 1 element only in the navigation header

Hello Treehouse community,

I hope you can help me to find the solution. I am trying to change the hover-over color of 1 element only in the navigation header, as a simple exercise.

I know how to change the color of any links in CSS using specific tags. For instance, this is something that I built from my very first HTML course. (the .tag class simply creates a grey background around the text)

<header>
 <h1 class="tag google" > This is a link to <a href="http://www.google.com" target="blank">Google.</a></h1>
      <h1 class="tag green" > This link is <a href="#" target="blank">Green.</a></h1>
      <h1 class="tag location">My home is Portland, Oregon.</h1>
</header>

In my CSS, the base color of every link and the hover-over effect is defined by:

a {
  text-decoration: none;
  color: #0499ff;
}

a:hover {
  color: #6633ff;
}

That being said, I can specifically control the link and hover-over colors for the classes "green" and "Google" with this CSS:

.green a {
  text-decoration: none;
  color: green;
}
.green a:hover {
  text-decoration: none;
  color: yellow;
}
.google a {
  text-decoration: none;
  color: pink;
}
.google a:hover {
  text-decoration: none;
  color: brown;
}

Now, the problem comes for the header navigation. The HTML for my header is the following:

<div class="main-nav">
        <ul class="nav">
          <li class="name">TEST</li>
          <li><a href="#">Home</a></li>
          <li><a href="new site.html">Second Site</a></li>
          <li class="photos"><a href="#">photos</a></li>
          <li><a href="#">Contact</a></li>
        </ul>
    </div>

The CSS of the hover-over effect would be the following:

.nav a:hover {
  color: white;
}

I've assigned a tag to my photos link, which I want to make it orange when I hover-over. The CSS would be:

.photos a:hover {
  color: orange;
}

But it doesn't work. I also tried the following without getting any results. I am not sure what I should do!

.nav .photos a:hover {
  color: orange;
}

Thanks for your time!