The Core

> 3 lines of CSS

Can you share?

I just mean a couple of simple media queries. Let's say I want your image method to show on anything smaller than an iPad.

Assuming I have something like

<div class="big-screen-form">
 <form>Stuff</form>
</div>
<div class="jason-method-for-small-screen>
 <a href="mailto:me@mail.com"><img></a>
</div>

Then my CSS is simply

.jason-method-for-small-screen {display:none;}

media only screen and (max-width: 767px) {
  .big-screen-form {display:none;}
  .jason-method-for-small-screen {display:block;}
}

So it's three lines of CSS not counting the media query. Obviously you would need more CSS to style the elements, but that would show/hide based on screen size. If you want iPads included, then you would use a max-width of 1024.

And note that if the AMP thing ever catches on, the <form> element will be disallowed on mobile, so you'll definitely need this

https://github.com/ampproject/amphtml/blob/master/spec/amp-html-format.md

https://www.webmasterworld.com/google/4779275.htm

https://www.ampproject.org/

Lots of places but any RTB system should give you access to remnant unsold space.

I personally like Adult traffic and adult pops (most probably related to buying so much in former professions for gambling stuff) and can vouch for people like http://www.trafficjunky.com/ but tghen again I am the guy that signed off on a GBP 7 Figure deal with Kim Dotcom on his Mega stuff, not long before he got arrested..... so take what I say with a pinch of salt