If you want to use download some website contents such as html pages, css and java script files for offline viewing, you can easily download entire website using wget on ubuntu command line.
Make sure you have Wget installed. Wget is a non-interactive commandline network downloader tool.
$ sudo apt-get install wget
Now, lets assume you want to download, “http://example.com/” , you can use your own domain instead of example.com, then use below command,
wget \ --recursive \ --no-clobber \ --page-requisites \ --html-extension \ --convert-links \ --restrict-file-names=windows \ --no-parent \ http://www.example.com
This will go on downloading entire website in your current directory.