From Wikipedia:
Catholics are expected to dress modestly,[8] The wearing of a headcovering was for the first time mandated as a universal rule for the Latin Rite by the Code of Canon Law of 1917,[9] which code was abrogated by the advent of the present (1983) Code of Canon Law,.[10] Apart from that, there have never been any “official” guidelines issued by the Catholic Church. But, from time to time the Church hierarchy, and even some popes, have given opinions on various matters; although these “guidelines” are not binding on Catholics, many tradition-minded Catholics find them persuasive.[11] Pope Pius XII stated that women should cover their upper arms and shoulders, that their skirts should cover at least as far as the knee, and the neckline should not reveal anything.[12] Another example is Giuseppe Cardinal Siri of Genoa, who stated that trousers were unacceptable dress for women.[13] Many tradition-minded Catholics have attempted to further expand on this latter standard.[14]Some Catholics have attempted to form cohesive theories of modesty. Sometimes this is from a sociological perspective,[12] while at other times it takes a more systematic, Thomistic approach, combined with the writings of the Church Fathers.[15] Approaches arguing primarily from traditional practices and traditional authorities, such as the saints, can also be found.[16]
The Church also expects men to dress modestly, but the demands are not as strict for them as for women; this is largely because men are often thought to be more inherently susceptible to sexual thoughts.
Pay special attention to the red. Those placed in authority over us have spoken over, and over, and over again about dress. Does the pope really need to declare an infallible statement that should be common sense in order to get people to listen?
If you truly believe that our Church accepts the culture of today, simply read any statement from the Holy Father over the last five years or so. We are continually fighting the culture because it is corrupt.