As mentioned in commit 5311daadf, there are several reasons to use
buttons in these situations. And, as mentioned in the previous commits,
using buttons instead of links for actions requiring confirmation will
help us test for accessibility issues.
Since we're adding styles for this button, we're also adding the
`font-size` property instead of using the `small` class. We'll deal with
the `float-right` property in the next commit.
This way it's going to be easier to style the link on focus, since
styles like `box-shadow` weren't working properly when we had an inline
link with block elements inside, and adding the `display: inline-block`
element to the link didn't play well with the layout we were using for
the recommendations.
We're also fixing the focus outline on recommendations, which didn't
look properly because of the border added with:
```
.recommended-index {
// (...)
@include full-width-border(top, 1px solid #fafafa);
}
```
The border was on top of the outline, breaking it. Increasing the
`z-index` of the element containing the outline solves the issue.
In a similar way, we're making sure the button to hide recommendations
stays visible so it's easier to click it.
