CSS alone cannot be used to hack a website or cause any harm to a server. However, it's worth noting that CSS can be used in conjunction with other web technologies to potentially exploit vulnerabilities in a website or server. For example, if an attacker can inject malicious CSS code into a web page, they may be able to use it to steal sensitive data or execute other malicious actions. This type of attack is known as a "cross-site scripting" (XSS) attack.