<link rel="stylesheet" type="text/css" href="/static/style.css"  >

package com.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MvcConfig implements WebMvcConfigurer {

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry){
    registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
}