Improvements to the Welcome Box

[mapk]

The Welcome Box needs a few revisions.

1. Move the 'edit' link up next to the 'X' (close) link in the grey box.
2. Make sure the padding is equal above and below the text in the grey box.
3. Make sure the columns in the grey box align with the columns in the main content below.

Here's an image displaying these changes, but only highlighting the column misalignment.

[mapk]

In 3671:

Breathe: Improvements to column spacing, alignment, and edit link in the Welcome Box.

Fixes #1836

[obenland]

In 3672:

Breathe: Abstract and re-use existing styles.

See #1836.

[mapk]

In 3673:

Breathe: Minor revisions to edit link for welcome box.

See #1836

[mapk]

In 3674:

Breathe: CSS version change to bust cache.

See #1836