I have no idea where everyone gets their immodesty standards from. Pius XI settled it already. If the skirt is barely below the knee, then it CANNOT be called decent. What is so complicated about this rule?!

This is a perfect illustration of what I'm talking about.  I will make this post and then be done with this thread.  This is an utterly ridiculous oversimplification of moral theology ... and that's why laymen should not be imputing sin to others who do not measure up to how they have formed their own consciences.  It needs to be left up to priests who have been properly trained to guide people in their moral lives and who have the authority, right, and obligation to do so.

Catholic Church teaches (based on divine law) that it's sinful to work on Sundays.  I see someone mowing his lawn on a Sunday and proceed to wag my finger (and tongue) at him that "look, a mortal sinner!"

If this isn't exactly what the Pharisees did, then I don't know what is.

But Catholic moral theologians teach that there can be proportionate reasons that justify working on Sundays, and the reason would be proportionate to the amount of work being done.  Is 5 minutes of work a mortal sin?  Is 15 minutes?  Catholic moral theologians generally give about 2 hours as a rule of thumb for when it would become a mortal sin.  But that's if you have no reason to do so.  If you go work 8 hours at a job because, say, you're an ER doctor and someone has to cover the ER, that's not a sin at all.  Or, if a man goes to work at a second job on the weekends (including Sundays) because he's struggling to pay his mortgage or other bills, then he may be permitted to do so.  If a man is mowing the yard of an elderly neighbor and doing it on Sunday because it's the only free time he has left, then that's permitted.  If someone needs to spend 10 minutes taking out garbage because Monday morning is their garbage pickup day, then that's permitted.  Some theologians say that it's permitted to go to a department store to buy things necessary for your own licit activities.

Look, if you want to hire a "Sunday Jєω" so that you don't have to lift a finger on Sundays, that's your business, but don't wag your finger at someone and denounce them as a sinner simply because their conscience is not formed as rigorously as your own.

Same kinds of proportionate reason standards apply to modesty.  The greater the immodesty, the graver the proportionate reason must be.  Unless there's some issue with these skirts flying up and showing panties, they are only slightly immodest and do not need a serious proportionate reason to justify doing them.  If some guy gets tempted to impure thoughts by a girl with a skirt/pant (whatever it is they're wearing) one inch above the knee while the knee itself is covered with a knee pad, then he's got bigger issues.  If someone believes that by wearing such an outfit a girl is practically a streetwalker and is being turned into a whore right before our eyes, then the person has some mental issues.

Padre Pio said skirts and dresses 8 inches below the knee.  He refused to give a woman absolution because she had a clothing shop that sold ladies slacks.  

Oh, Ladislaus, now you're attacking those who disagree with you and charging that we're "imputing sin" on others?  You yourself said that, most likely a venial sin was committed by slightly immodest attire.  You discussed venial sin a few times on this thread. 
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This discussion started off by talking about a REAL LIFE example, but then you muddied the waters by inserting theoretical principles and distracting from the discussion.  Now we're fully talking about theory and the mini-skirt picture you posted, and you've illogically circled back to saying we are "imputing sin" on others?  How, pray tell, does one impute sin on a hypothetical person?
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You're all over the place on this.  You've gone back and forth between a real life example and theory and this thread could've made more sense if you could stick to one or the other.  ...or at least you could be more clear when you mentally switch, as many times, it's not clear.  Then you unnecessarily fight with people who are talking one vs the other.

If some guy gets tempted to impure thoughts by a girl with a skirt/pant (whatever it is they're wearing) one inch above the knee while the knee itself is covered with a knee pad, then he's got bigger issues.  If someone believes that by wearing such an outfit a girl is practically a streetwalker and is being turned into a whore right before our eyes, then the person has some mental issues.

You're arguing against the wind.  No one has said the above in any way.

What people wear socially is public knowledge and is plain for all to see.  There are no "facts and details" which explain away immodest dress, except for extreme circuмstances.  99% of the time, what people wear is of their own choosing, so the only defense for immodest dress is a faulty conscience, which is not an moral excuse, because it's a form of ignorance that is morally culpable.

It is good that he triggered you to respond like you have, I could post here all of your responses from the beginning to teach people modesty, and one would see how you went perfecting the methods of communication to get across to him and others. Keep up the good work.

If you read how strongly St John Vianney opposed dancing 200 years ago, then ask yourself what he would do with a girl in a miniskirt playing sports, you will come to a definitive answer about the whole issue.
The BVM held him up as THE model priest. We should listen to her and him.

I wonder what happened with this.