codepen 1 I used an article to wrap div2 and div3 in so they would stay in the proper order when they were floated right.
codepen2 Using display: block; on all the div elements put them each on their own line. Then I added margins to div2 to center it. And floated div3 right.
codepen3 Div2 is nested inside div1 and positioning is determined by margins. Color was chosen using colorzilla in chrome.
codepen4 div1 is positioned relative and div2 is positioned absolute with top and left set to 75px.
codepen5 Similar to challenge 2 but float div1 right and apply clear:both to all divs so they maintain their block positioning.
codepen6 I did a bunch of stuff and eventually it worked. I wrapped the divs in a section. I made the section position:relative. Then I made div1 position:absolute and positioned it on the page. The other two divs are inside of div1 and floated left and right.
codepen7 div2 is floated right inside of div one and moved down with margins.
codepen8 div2 is floated right inside of div1.
codepen9 I put div2 and div3 inside of div1. I did cool relative/absolute positioning that you showed us.
codepen10 ##This is awesome.
codepen 15 not finished yet.