Download the theme from the theme store
https://www.odoo.com/apps/themes/11.0/backend_theme_v11/
This will contain 2 files which you need to add into your addon directory. If you installed with Bitnami then it’s in
/apps/odoo/data/addons
You need to copy the 2 files into that directory. The configuration file by default does not include this directly so you need to add it.
/apps/odoo/conf/odoo-server.conf
The first line should say “addons_path.” At the end of that line add a comma (,) and then the full path to your addon directory.
addons_path = /home/ubuntu/odoo-11.0.20171118-2/apps/odoo/lib/odoo-11.0.post20171118-py3.6.egg/odoo/addons, /home/ubuntu/odoo-11.0.20171118-2/apps/odoo/data/addons/
In Odoo go to the settings page and look for “Activate the developer mode” and click that
Then go to “Browse Apps” and remove the “Apps” from the search bar and search for theme. You may need to click “Update Apps List” if it doesn’t show up automatically.
Update: 06-12-2019 Icons Missing from Menu FileNotFoundException web_responsive
When I installed web_responsive I had some of the permissions wrong for the addon directory. Once I fixed the permissions I was unable to get the icons for the menu to show up. The files were not created in the filestore and no quantity of restarts or reinstalls would resolve the issue. Ultimate I stopped the service, added the update all flag to the service, and restarted the service. Update all took a few minutes to complete. Then I removed the update all command and restarted the service
sudo systemctl stop odoo11.service /home/odoo11/odoo11-venv/bin/python3 /home/odoo11/odoo/odoo-bin -c /etc/odoo11.conf --update all sudo systemctl daemon-reload sudo systemctl start odoo11.service