This was an ever-changing era.
Every day it seemed some changes were quietly happening, many people at the time did not take special notice, but when they took a moment to reflect on the past, they would be shocked to discover that their lives had changed dramatically without their realization.
Take for example the well-known "three big items" for marriage, what were the original three big items? A watch, a bicycle, and a sewing machine. Back then, anyone who could ride an old type of bicycle was considered incredibly cool.
Those who had lived through that era, or had seen related TV shows and movies knew that even in the Imperial City, bicycles were ubiquitous. And the most fashionable and rebellious youths at the time were fond of breakdancing, which nowadays looks very outdated. So back then, riding a bicycle and shouting to go breakdancing was considered trendy.