rotationY 90 not stopping where expected

[sitherikb]

Two questions about my sketch.

 

[1]

I expected my tween to rotation: 90 to stop directly on top of the white line in my sketch.  

What am I doing wrong?

Note: there are going to be many of these planes spinning around together so I applied "perspective" to the parent #a instead of transformPerspective (as described here https://greensock.com/css3/ )

 

[2] 

What values would I adjust to make the bottom of the red panel never dip below the bottom of the blue line?  It is okay if the panel swings above the top green line.  I want it to look like the "camera" is on the floor, watching a door open.

 

See the Pen bdQrVQ by jedierikb (@jedierikb) on CodePen

[Carl]

I quickly got this to work (i think) in Chrome and Safari: http://codepen.io/GreenSock/pen/WvYERW

 

not really sure what other browsers need.