Christian modesty is more than a dress code. It starts with an inward disposition of shamefacedness and godliness. This disposition, in turn, should govern clothing choices.
Proverbs 7:10-12 says:
And, behold, there met him a woman with the attire of an harlot, and subtil of heart. (She is loud and stubborn; her feet abide not in her house: Now is she without, now in the streets, and lieth in wait at every corner.)
Notice, the attire of an harlot, included a loud and stubborn disposition. She is also, not content with being a "keeper at home" - her feet must abide elsewhere. Finally, her inward disposition governed her choice of clothing, and she chose the attire of an harlot.
Also consider 1 Samuel 16:7
for the LORD seeth not as man seeth; for man looketh on the outward appearance, but the LORD looketh on the heart.
It's very clear that what's most important to God is the inward heart. But because man looks on the outward appearance, Christians should also take heed to what they wear.
I don't know of any Christian who would walk into a bank with a stocking over their head because they would fear being identified as a robber. Likewise, no man would show up for work wearing a long-flowing dress, because he would fear being identified as a woman.
Society is built on identity, and Satan is hard at work breaking down gender-specific identity, especially distinction in clothing.
Every culture in the world includes gender distinction in clothing. The names of the articles of clothing may change from culture to culture, but gender distinction in that clothing is still evident and relevant for today.
In every society, where God shows up in the hearts of believers, you can see gender distinction in dress.
As tough as this issue is to talk about, it's really a simple problem to identify. The problem isn't legalism in the church, it's rebellion against God's principles of distinction in dress.
To get back "to normal" Christian boys and men should consider only wearing distinctively masculine apparel; likewise Christians girls and women should consider wearing only distinctively feminine apparel.