<p>You need to place your CSS code inside the <code>&lt;style&gt;</code> tag, like so:</p>

<pre><code>&lt;style&gt;
    .arxiv_button {
        background-color: #4CAF50; /* Green */
        border: none;
        color: white;
        padding: 10px 32px;
        text-align: center;
        text-decoration: none;
        display: inline-block;
        font-size: 16px;
        margin: 4px 2px;
        cursor: pointer;
    }
&lt;/style&gt;
</code></pre>
Google Search snippet showing CSS code
<p>I have very little experience with front end developing, so please be patient. I built a simple website, and uploaded it to my university's server. obviously, I most have done something wrong, since the snippet Google is </p>

<p><a href="https://i.stack.imgur.com/7Tljm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7Tljm.png" alt="enter image description here"></a></p>

<p>Which is CSS code. 
I changed my website about a week ago (to its current version, which I thought would fix the issue), so is there a chance that it is waiting for Google's indexing task to run again before showing the correct snippet?</p>

<p>In case not, what should I do in order to fix it? <a href="http://technion.ac.il/~omerbp/" rel="nofollow noreferrer">here is a link to my website</a></p>