`<td>` inside of `<del>` and `<ins>` should have coloured background

[SamWilsn]

Here's what we have now:

It should look more like:

[pheobeayo]

Can I take up this issue?

[SamWilsn]

Go for it!

[pheobeayo]

@SamWilsn please, which of the pages am I making these changes to?