Tanktop strap?

There's a particular style of outfit where the character's top is wide cut and you can see their bra straps. But oftentimes the straps are thick, more like a tanktop or something (like Futaba from Persona 5). I'm not actually sure how the outfit works, so I don't know how it should be tagged.

Examples:
post #3117338
post #3130670

Do you think this is just a tanktop under a dress/shirt? And is there a tag for this (or should there be)?

I've been tagging ones where the straps appear to be part of the outer garment with shirt_straps. That applies to the first, but the second looks like separate articles of clothing, and the thickness is more like a sports bra than a tank top.

Also as applicable, I tag off-shoulder dress or off-shoulder shirt.

Hmm, interesting. I guess it's ambiguous sometimes. I see that post #3123874 is tagged as bra_strap, but it could feasibly be shirt_straps since the color is the same. For that one, the width makes it look more like a bra strap, but I think I see how it works now.

Looking more closely, something like post #3144626 might be another sports_bra, while post #3127083 is anyone's guess. Feels a bit more like shirt_straps because the top of the bra might be visible otherwise.