I am trying to make a div with a `height: calc(100% - 80px)` and an `overflow: scroll`. The div is completely ignoring both of these rules. Here is what I have attempted:

```css
.tab-content {
    clear: both;
    height: calc(100% - 80px);
    overflow: auto;
}

#tutorial {
    padding: 5%;
}
```

```html
Tutorial

<div id="tutorial" class="tab-content">
    Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
    <br> Tutorial content
</div>
```

Please alert me of where I am going wrong and how to fix the problem.