Question: I can’t get `padding-bottom` to work when I use `overflow-y: auto` on a box. I use Firefox.

```css
#container {
  padding: 3em;
  overflow-x: hidden;
  overflow-y: auto;
  width: 300px;
  height: 300px;
  background: red;
}

#some_info {
  height: 900px;
  background: #000;
}
```

```html
<div id="container">
  <div id="some_info"></div>
</div>
```

See the [JSFiddle](https://jsfiddle.net/rwgZu/).

Answer: 
You just need to add `box-sizing: border-box` to the same element where you applied the `overflow` rule.
I think `@-moz-document url-prefix()` is what you need.

```css
#container {
    padding: 3em;
    overflow-x: hidden;
    overflow-y: auto;
    width: 300px;
    height: 300px;
    background: red;
}

#some_info {
    height: 900px;
    background: #000;
}

@-moz-document url-prefix() {
  #container > :last-child {
    margin-bottom: 3em;
  }
}
```

```html
<div id="container">
  <div id="some_info"></div>
</div>
```