I'm trying to move the first line matching a pattern to a different
(and fixed) line position. For example, I would like to move line
number 4 to position number 3. How do I do this? I'm totally lost. Any
help would be highly appreciated.

Ciba Vision Contact Lenses
Ciba-Vision-Contact-Lenses-.html
<p class="headline1">Ciba Vision Contact Lenses </p>
Ciba vision contact lenses promise you healthy and clear eyesight,
which will help you devour all the beauties that life has in store for
you. Ciba vision contact lenses and lens care products are available in
70 countries worldwide, meeting the visual needs of millions of
customers who express great satisfaction after using them.
<p class="maincopy">Ciba vision contact lenses promise you healthy and
clear eyesight, which will help you devour all the beauties that life
has in store for you. Ciba vision contact lenses and lens care products
are available in 70 countries worldwide, meeting the visual needs of
millions of customers who express great satisfaction after using
them.</p>