We're about to put in an order for a bunch of Hunter Douglas cellular blinds to replace all blinds in the upstairs' rooms of our house. All of the new bedroom blinds will be "room darkening" (and we'll use light filtering versions in the bathrooms). I'm trying to make it so that the bedrooms will be as dark as possible when the blinds are closed (several of us are light sleepers, no pun intended). We already purchased one set of blinds for a closet window (just to make sure we liked it prior to ordering all of the blinds for the rest of the upstairs). The currently installed one looks/works fine, aside from the slight light gaps on the sides. (If that turns out to be a problem, I'll add drapes later.) We're mostly going with simple "bottom up" blinds - but there were a couple of rooms where I thought "top down bottom up" might be nice. Sorry for the "long-windedness" - but here is my question: There are no light gaps at the bottom or at the top, when the "bottom down"blinds are closed. I'm not clear on how the top of a "top down" blind would affix to the top of the window area. Will I be introducing a light gap at the top, if we install blinds that can also go "top down"? Thanks, in advance. - Tammy