Position absolute but relative to parent

I have two divs inside another div, and I want to position one child div to the top right of the parent div, and the other child div to the bottom of the parent div using css. Ie, I want to use absolute positioning with the two child divs, but position them relative to the parent div rather than the page. How can I do this?

Sample html:

<div id="father">
   <div id="son1"></div>
   <div id="son2"></div>
</div>

#father {
   position: relative;
}

#son1 {
   position: absolute;
   top: 0;
}

#son2 {
   position: absolute;
   bottom: 0;
}

This works because position: absolute means something like "use top, right, bottom, left to position yourself in relation to the nearest ancestor who has position: absolute or position: relative."

So we make #father have position: relative, and the children have position: absolute, then use top and bottom to position the children.

div#father {
    position: relative;
}
div#son1 {
    position: absolute;
    /* put your coords here */
}
div#son2 {
    position: absolute;
    /* put your coords here */
}

Incase someone wants to postion a child div directly under a parent

#father {
   position: relative;
}

#son1 {
   position: absolute;
   top: 100%;
}

Working demo Codepen