Australia is pulling the plug on its teens' social media habits. The country enacted the world's first ban on social media for children under 16 this week, threatening tech giants with multi-million-dollar fines if they fail to take "reasonable steps" to kick underage users off their platforms. Officials say the crackdown targets the site's "design features that encourage [young Australians] to spend more time on screens, while also serving up content that can harm their health and wellbeing."