Very nice website, Miss Danvers. In the future you might want to add production notes and links to other Supergirl movie sites.
Supergirl's movie costume could merit its own section, since this was later modified for the post-Crisis Matrix. In fact, due to the movie and the long Matrix/Linda Lee run (which can be purchased at costume shops) the general public probably recognizes THIS uniform as THE "Classic Supergirl", even though the Silver Age Kara Zor-El never actually wore it in the mainstream DC titles! (She did wear this in three comic books published by DC -- the movie adaptation of course, and two "Seatbelt Safety Specials".)
And if you look at
http://superman.nu/supergirl/costumes/1983/, you'll find that this WASN'T the original movie design -- in fact, Supergirl flew to her destiny in the Crisis wearing the costume first intended for Helen Slater!
A side-by-side comparison of the Helen Slater and Matrix costumes shows that Matrix's costume
1. Has pointed sleeves.
2. Has belt loops and sharper "V" cut on skirt beltline and hemline.
3. Depending on artist, the top of the "S" shield touches the collar.
4. Different-shaped boot tops ("V" notch in front) lacking gold trim.
5. Lacks bracelet on left wrist.
However, the blue top/red skirt combo worn by Helen and Matrix became so associated with Supergirl that during the "Many Happy Returns" arc the colorists occasionally goofed and gave the time-displaced Kara Zor-El a red skirt instead of her original all-blue ensemble! This was mostly corrected in the trade paperback.
Again, best wishes on your new site.