okay. firstly, to clarify, i am autistic and randomly get obsessed with something to the point i will do immense research and not be able to think of anything else for a couple of hours or more. now we've established that, i've been analysing the hogwarts uniforms and have Thoughts.
i am ignoring that hat. i dont like it. no one wears it after like,, the first scene. it doesn't exist to me. now, as we know the uniform is; black/dark gray smart trousers or dark grey skirt, house coloured jumper or cardigan (optional), white shirt, house coloured tie, house coloured robe (optional), house coloured scarf (for outside use only), black/grey tights (optional), smart black shoes, black gloves (for outside use only).
however they used to have grey blazers in the uniform (as seen pictured, i apologise for having to show you that sirius). why they got rid of it? who knows. but it must have been some time between the marauders 5th year to harry's first year. personally i like to think it was during the marauders last year and remus cried at the loss.
in terms of houses, gryffindor's seem to appear the messiest as a group, and the slytherin's the neatest. also the slytherin's seem to have this little snake pin for their ties which no one other houses get (can't see it too well in the photo but it's literally just this tie pin with a little snake). i wholeheartedly believe walburga and orion are responsible (the above picture of tom riddle shows him without a pin so they didn't have them in the past). so when regulus got into slytherin they gave him the slytherin pin to sorta,, take a dig at sirius for not being slytherin and it soon became a Thing for pureblood parents to gift their child a snake tie pin when they get into slytherin.
now, to apologise for showing the canon sirius, i shall describe what they'd actually wear (you think sirius would wear the blazer? and the robe? and the tie that neat? get real.) only sirius in first year would basically look more like hermione (but obviously with the blazer since i guess they had blazers back then), but the rest of the time it gets more and more messy and rebellious- they stop wearing the jumper, blazer and cloak. if it's cold they wear remus' jumper and/or their leather jacket. their tie and shirt is like ron's in the photo. they sometimes wear the skirts, sometimes flared trousers. always wears boots. lots of jewellery, very 70s punk/rock vibes basically and breaking like every uniform rule.