title: Border-top on input element is not "straight"
body: <p>I'm applying a CSS border to an input element and then applying a thicker <code>border-top</code> styling. Why does this have a strange overlapping effect?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>input {
    width: 50%;
    border: 1px solid #ccc;
    border-top: 15px solid #414042
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;input type="text" placeholder="NOME" required&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p><strong><a href="http://jsfiddle.net/npq7kq9z/3/" rel="nofollow noreferrer">JSFIDDLE</a></strong></p>
  
  <p>Here's a detail of the top-left corner:<br>
  <img src="https://i.stack.imgur.com/vPm0Y.jpg" alt="enter image description here"></p>
  
  <p>Why does this happen and how can I fix it?</p>