maddy, since you're using the cream color on the shower walls, why not use a cream color quartz piece for the curb? You can buy quartz backsplash pieces separate. (they use them on vanities).
i've used them on some showers I've done.
this was a 6" quartz backsplash piece (I think it was either 6' or 9') that we cut to fit the curb
It just happened to be a nice charcoal to match the floor tile. This wa another one I had on hand. (the dark one) It's just a backsplash piece you can buy for $60
for my own shower I did a solid piece of marble on top (to match the outside floor) but on the inside I ran the white subway tile right up underneath it on the curb portion
so if you did the blue on the floor, ran your cream on the inside of the curb, and topped it w/a matching ivory/cream piece of quartz, I think it would look very nice
of course you could run your tiles on the curb, but it's just more grout to clean and water to worry about that drips down from the glass doors.
tracks get mucky. think about using the plastic water guards that slide on the glass. they remove easily for cleaning, and you can replace them every few years.
If you aren't doing a door, I'd say do it like this. Or like Helens.
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Transition between floors
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