CLAMP's animation really is top-notch and always ahead of its time, in fact, it's one of the few companies that draw the eyebrows behind the hair, instead of above it, so it's actually a pretty realistic style of drawing.
Card captor Sakura is really one of the most famous animes ever done, and a must see for most teen people, however even adults can enjoy that atmosphere... I don't know why, but I always felt so relaxed when watching it...
Never noticed it though, but it's just like you said: Tomoyo has magical powers!!! how come she always chooses the perfect costume?!?!?! OMG a hidden secret!!!