I noticed a video showing young students finishing a course on memorizing al-Qur'an al-Karîm. I was saddened to see that the students were wearing western hats. All of these hats were forbidden in widely-used classical texts written or adopted by Sunni scholars in the Osmanlı (Ottoman) times. I will give pictures from books written at different dates and will provide translations at a suitable time.
The following is from Kâdîzâde Ahmed Efendi [Qadizada Ahmad Afandi] (d. 1783), Birgivî Vasiyetnamesi Kâdîzâde Şerhi [Birgivî Will and Testament Kâdîzâde Commentary], Bedir Yayınevi [Bedir Publishing], Istanbul 1988, p.200:
From the famous basic aqida and fiqh book Miftahu'l-Janna known as "Mızraklı İlmihal" and widely distributed and read during the Osmanlı (Ottoman) times: