I'm trying to move the footer down 50px to go outta screen,
but the negative margin doesn't work (nothing is moving) and I'm not quite sure why...

```
footer {
  background: #111;
  padding: 50px 0 100px;
  text-align: center;
  margin-bottom: -50px;
}

```

Here's an example 

```css
body {
  background: white;
  margin: 0;
}

section {
  height: 100vh;
}

footer {
  background: green;
  padding: 50px 0 100px;
  text-align: center;
  color: white;
  margin-bottom: -50px;
}
```

```html
<body>

  <section>
    Section 1
  </section>

  <section>
    Section 2
  </section>

  <footer>
    <div>
      some content here
    </div>
  </footer>

</body>
```