Fixes #32 - Adjustments to cross-promotion section

Please see
https://gitlab.com/eyeo/websites/web.adblockplus.org/issues/32#note_63026898
before reviewing.

[juliandoucette, 2018-03-13 16:56:02]

Please see
https://gitlab.com/eyeo/websites/web.adblockplus.org/issues/32#note_63026898
before reviewing.

[ire, 2018-03-14 07:57:47]

On 2018/03/13 16:56:02, juliandoucette wrote:
> Please see
> https://gitlab.com/eyeo/websites/web.adblockplus.org/issues/32#note_63026898
> before reviewing.

Ack

[juliandoucette, 2018-03-14 12:27:33]

New Patchset up! (It's ready to be reviewed now)

Detail: I added another layer of responsiveness to heading sizes globally in
this change.  If you agree to this change then we may consider pushing it
separately to avoid confusion. 

I like this change because it's hard to fit large headings on small devices. And
reducing the font-size makes the ~large line-height (which I think is good for
accessibility) less of a problem.

[juliandoucette, 2018-03-14 12:48:34]

On 2018/03/14 12:27:33, juliandoucette wrote:
> Detail: I added another layer of responsiveness to heading sizes globally in
> this change.  If you agree to this change then we may consider pushing it
> separately to avoid confusion. 
> 
> I like this change because it's hard to fit large headings on small devices.
And
> reducing the font-size makes the ~large line-height (which I think is good for
> accessibility) less of a problem.

Scratch that. This change is also relevant to the hero-unit section. Therefore,
I will address it separately in another review.

[ire, 2018-03-14 13:17:11]

@jeen:
> @juliandoucette for the phones I would reduce the line height by 0.5em and
reduce the font size of the header by about 0.2em - or to the best of your
judgement.

You didn't address this?

[juliandoucette, 2018-03-14 13:55:46]

On 2018/03/14 13:17:11, ire wrote:
> You didn't address this?

See my last two replies and https://codereview.adblockplus.org/29722720/.

[ire, 2018-03-14 14:12:39]

On 2018/03/14 13:55:46, juliandoucette wrote:
> On 2018/03/14 13:17:11, ire wrote:
> > You didn't address this?
> 
> See my last two replies and https://codereview.adblockplus.org/29722720/.

Ack. Must have missed it, sorry.

LGTM

[juliandoucette, 2018-03-14 14:58:40]

Done https://hg.adblockplus.org/web.adblockplus.org/rev/5b0e604843d1