Hong Kong (CNN) When protesters in Hong Kong targeted the Chinese government's headquarters in the city , social media users in China were united in outrage.

"The dignity of our motherland won't be allowed to be trampled," one person wrote on Weibo, the country's highly-censored equivalent to Twitter , while another warned the young protesters that "playing violently is how you seek death."

A third commenter sought to reassure others, writing that "the central government promised that Hong Kong won't be changed for 50 years. There's only 28 years left before Hong Kong becomes part of (China)."

That 2047 deadline, on which the clock began ticking after the United Kingdom handed Hong Kong over to China in 1997 , is at the forefront of the minds of the mostly young protesters who have been taking to the streets for almost two months now, in increasingly violent confrontations with police and pro-government groups

What began as protests over a now-suspended extradition bill have broadened to cover a host of demands , including calls for greater democracy and more government accountability, that many feel they are running out of time to achieve.

Even as democratic values have increasingly come under threat around the world, and many voters in democracies are increasingly expressing apathy or despair, young Hong Kongers are determined to continue a fight for freedom which began decades ago under British rule, before time runs out and Hong Kong becomes just another Chinese city.

"Liberate Hong Kong, the revolution of our times," they chanted on Sunday.

Treaty city

Much of what people usually think of as Hong Kong -- the island on which the city's financial district sits, and the Kowloon Peninsula -- was ceded to the the British Empire by the Qing Empire following its losses in the Opium Wars of the nineteenth century.

More than 86% of the land in modern Hong Kong, however, is in the New Territories, which the UK leased from China for 99 years in 1898. That lease was due to run out in 1997, prompting negotiations which eventually led to the entirety of the city being handed over to Chinese control

No Hong Kong residents were party to the discussions, nor were they consulted about the final decision, which had a profound effect on their futures and freedoms.

The agreement , signed by British Prime Minister Margaret Thatcher and Chinese Premier Zhao Ziyang in 1984, included the proviso that "Hong Kong's previous capitalist system and life-style shall remain unchanged for 50 years."

This would be achieved by the "one country, two systems" principle, suggested by paramount leader Deng Xiaoping, by which Hong Kong would be both part of China and separate, retaining the limited democratic freedoms its citizens had fought for under British rule.

While declassified documents show little concern among Thatcher's negotiating team for the people of Hong Kong -- rather than the city's continued economic success -- most at the time expected China would have itself democratized by 2047 when the agreement ran out, and so the end of "one country, two systems" would be moot.

By the time 1997 rolled around, the Soviet Union had collapsed and China under Deng was rapidly opening up. Despite the terrifying events of the 1989 Tiananmen Massacre, which helped reignite Hong Kong's pro-democracy movement, the general feeling was that China was headed towards eventual political as well as economic reform.

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No way out

Hong Kong has changed dramatically in the more than two-decades since handover , and many of the fears of imminent collapse or brutal authoritarian crackdown have not panned out.

China too has changed. In the decades since 1989, the economy has exploded, becoming the second-largest in the world as China took its place as a global superpower. The Communist Party has shown no signs of lessening its grip on the country however, and political repression and control has only increased under Chinese President Xi Jinping.

Xi has expanded the size of the military and cracked down heavily on any signs of separatism or even non-Chinese identity in places such as Xinjiang or Tibet. He's also advanced a much harder line on Hong Kong.

During a defense briefing this week, a spokesperson said China's military, known as the People's Liberation Army (PLA), was watching the situation in Hong Kong closely, and pointed to a Hong Kong law that allows the local government to request assistance in maintaining public order from the military garrison in the city.

Such statements are greeted with no small amount of alarm by young Hong Kongers, who are the most alienated from China of any generation, despite concerted efforts by both the local and central governments to inculcate greater levels of patriotism.

Many older Hong Kongers, including pro-democrats, who grew up in a British colony, strongly identify with China and saw a point of pride in the city returning to Chinese rule. Today, the number of people who express pride in being a Chinese citizen is at a record low , with a significant number of young people identifying as Hong Kongers rather than Chinese, according to the Hong Kong University Public Opinion Program.

For those who identify as Hong Kongers, and may support Hong Kong independence, the idea of being fully absorbed by what they view as a foreign country is terrifying, let alone a country as authoritarian as Xi Jinping's China.

Undoubtedly 2047 seemed like a long way off for those overseeing Hong Kong's handover, and remained impossibly distant for much of the city's early political development, but for the student protesters flooding the streets this year, it is very much on the horizon -- 18-year-olds today will be 46 when the city becomes fully Chinese.

Unlike many millennial Hong Kongers -- whose parents moved abroad in the years running up to handover, taking advantage of generous immigration laws within the British Commonwealth to get their children foreign passports -- they also have no way out. This is their home and they're stuck here, like it or not, so they may as well try to fix it.

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Stalled progress

Traditionally there were two ways of fixing Hong Kong -- through the legislature, and through street protests -- but both have come under increasing pressure in recent years and proven less than effective.

After China rolled back last-ditch democratic reforms introduced by the UK's final colonial administration, Hong Kong was left with a flawed and partial democracy in which around 50% of the legislature is freely elected , with the rest chosen by "functional constituencies," business and industry groupings which tend to be strongly pro-Beijing. The city's leader is not elected by the people but is appointed by a Beijing-dominated "selection committee."

In 2014, student led street protests, known locally as the Umbrella Movement, sought to change how the city's leader was chosen. The movement failed, and in intervening years, the legislature has become a less effective place to push for change. Pro-democracy lawmakers have been expelled and more radical candidates barred from standing for office

These developments have left many younger people skeptical of the effectiveness of traditional political organizing and peaceful protest in pushing for change.

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The most dramatic example of the growing drive towards more radical, direct action was the storming of the city's legislature on July 1. Young protesters broke into and briefly occupied the building after an hours-long siege, despite an attempt by older pro-democracy lawmakers to talk them down.

Leung Yiu-chung, a 66-year-old pro-democracy lawmaker, was literally tackled out of the way as he attempted to prevent a makeshift battering ram being used to smash a door into the building.

"They questioned what could the legislature still achieve when even 2 million people have failed to budge the government," Leung said later , referring to the massive anti-bill march on June 16. "Sadly, I could not answer. These young people are in despair and they have no hope for the government any more."

Much of the language around the protests is growing increasingly fatalistic. Posters talk about dying for Hong Kong, and when asked protesters are fully aware of the risks of severe prison time if they are found guilty of rioting. Apparent suicides linked to the protests have led some to push back against what they warn is an unhealthy martyrdom complex growing among some circles

Despite this however, and despite talk of potential bomb plots and recent violence against protesters, the opposition movement shows no signs of slowing. At least two marches are planned for this coming weekend.

Whether Hong Kongers can achieve the democracy the city has spent decades fighting for is unclear, but for the young protesters taking to the streets, the window for doing so is shrinking, and the time to fight is now.