Download HTML page and its contents

You can use the urlib:

import urllib.request

opener = urllib.request.FancyURLopener({})
url = "http://stackoverflow.com/"
f = opener.open(url)
content = f.read()

What you’re looking for is a mirroring tool. If you want one in Python, PyPI lists spider.py but I have no experience with it. Others might be better but I don’t know – I use ‘wget’, which supports getting the CSS and the images. This probably does what you want (quoting from the manual)

Retrieve only one HTML page, but make
sure that all the elements needed for
the page to be displayed, such as
inline images and external style
sheets, are also downloaded. Also make
sure the downloaded page references
the downloaded links.

wget -p --convert-links http://www.server.com/dir/page.html

Function savePage bellow:

• Saves the .html and downloaded javascripts, css and images based on the tags script, link and img (tags_inner dict keys).
• Resource files are saved on folder with suffix _files.
• Any exceptions are printed on sys.stderr

Uses Python 3+ Requests, BeautifulSoup and other standard libraries.

The function savePage receives a url and pagepath where to save it.

You can expand/adapt it to suit your needs

import os, sys, re
import requests
from urllib.parse import urljoin
from bs4 import BeautifulSoup

def savePage(url, pagepath='page'):
    def savenRename(soup, pagefolder, session, url, tag, inner):
        if not os.path.exists(pagefolder): # create only once
            os.mkdir(pagefolder)
        for res in soup.findAll(tag):   # images, css, etc..
            if res.has_attr(inner): # check inner tag (file object) MUST exists  
                try:
                    filename, ext = os.path.splitext(os.path.basename(res[inner])) # get name and extension
                    filename = re.sub('W+', '', filename) + ext # clean special chars from name
                    fileurl = urljoin(url, res.get(inner))
                    filepath = os.path.join(pagefolder, filename)
                    # rename html ref so can move html and folder of files anywhere
                    res[inner] = os.path.join(os.path.basename(pagefolder), filename)
                    if not os.path.isfile(filepath): # was not downloaded
                        with open(filepath, 'wb') as file:
                            filebin = session.get(fileurl)
                            file.write(filebin.content)
                except Exception as exc:
                    print(exc, file=sys.stderr)
    session = requests.Session()
    #... whatever other requests config you need here
    response = session.get(url)
    soup = BeautifulSoup(response.text, "html.parser")
    path, _ = os.path.splitext(pagepath)
    pagefolder = path+'_files' # page contents folder
    tags_inner = {'img': 'src', 'link': 'href', 'script': 'src'} # tag&inner tags to grab
    for tag, inner in tags_inner.items(): # saves resource files and rename refs
        savenRename(soup, pagefolder, session, url, tag, inner)
    with open(path+'.html', 'wb') as file: # saves modified html doc
        file.write(soup.prettify('utf-8'))

Example saving google.com as google.html and contents on google_files folder. (current folder)

savePage('https://www.google.com', 'google')