默认情况下，当您使用HTML Publisher插件发布任何报表时，不会显示CSS内容。Jenkins根据CSP（内容安全策略）阻止CSS。
参考：https://www.jenkins.io/doc/book/system-administration/security/configuring-content-security-policy/
启用CSS内容：Manage Jenkins -> Script Console并执行System.setProperty("hudson.model.DirectoryBrowserSupport.CSP", "")
启用CSS时，您会收到以下警告The default Content-Security-Policy is currently overridden using the hudson.model.DirectoryBrowserSupport.CSP system property, which is a potential security issue when browsing untrusted files.
要禁用它，只需重新启动Jenkins服务器。CSP将再次设置为默认值。

请求.css或.js时，可能会出现以下消息(blocked:csp)。

Refused to apply inline style because it violates the following Content Security Policy directive: "style-src 'self'". Either the 'unsafe-inline' keyword, a hash ('sha256-Epaif2cHkSx/K62AHKClT5geuHQeilAdJVvUuNPdcuw='), or a nonce ('nonce-...') is required to enable inline execution.

在这种情况下，您应该这样处理。暂时放宽内容安全策略。转到Manage Jenkins -> Script Console并在控制台中键入以下命令：

System.clearProperty("hudson.model.DirectoryBrowserSupport.CSP");
System.setProperty("hudson.model.DirectoryBrowserSupport.CSP", "sandbox allow-same-origin allow-scripts; default-src *; style-src * 'unsafe-inline'; script-src * 'unsafe-inline' 'unsafe-eval' ; font-src * data: ");