My entire header is a hyperlink, and I'm not sure why.

This is the first site I have attempted to put together on my own after going through the "Build a Website" course. Everything is actually going pretty good, but I can't seem to figure out this one.

In the code, I have a header element to house a h1, and h3 element. I used my hyperlink to bracket the h1 an h3, but it appears to have affected the entire header. ( I should note that this is not effecting my nav. just my h1 and h3 elements, as intended, as well as the entire length of the header, 100% of the page. I'm just looking to make the area near the actual text a hyperlink. )

here is the code

<a href="index.html">
    <h1>Website Name</h1>
    <h3>Under construction!</h3>
</a>
    <nav>
        <ul>
            <a href="index.html"><li>Home</li></a>
            <a href="shows.html"><li>Shows</li></a>
            <a href="funnies.html"><li>Funnies</li></a>
            <a href="about.html"><li>About</li></a>
            <a href="contact.html"><li>Contact</li></a>
        </ul>
    </nav>
</header> 

and the css

header { width: 100%; text-align: center; background-color:#666666;

h1, h3 { max-width: 500px; margin: 0 auto;

}

h1 { font-size: 4em; font-family: 'Roboto', sans-serif; }

h3 { font-size:2em; font-family: 'Kaushan Script', cursive;