Browser-sync how to set up a proxy?

Question

gulp.js

The essence of the question is, I want to set up a proxy for the site, so as not to copy the entire html, but only to correct the styles.
Here is the task, there are no errors, but the site does not connect styles

var gulp   = require('gulp');
var server = require('browser-sync');
var util   = require('gulp-util');
var config = require('../config');

gulp.task('server', function() {
    server({
        proxy: 'https://www.samesite.com',
        files: [config.dest.css + '*.css'],
        middleware: require('serve-static')('./build'),
        rewriteRules: [
            {
                match: new RegExp('</head>'),
                fn: function() {
                    return '<script async src="/browser-sync/browser-sync-client.js?v=2.18.13"></script>' +
                        '<link rel="stylesheet" href="/css/main.css" media="all"></script></head >'
                }
            }
        ],
        port: 8080,
        open: true  
    });
});