[SOLVED] Ubuntu 15.10 LXC iptables port forwarding question

I'm trying to port forward my host's port 80 to an LXC container running nginx. I have correctly installed both LXC on the host and nginx in a container, stated nginx in the container, and also used the lxc-info command to determine the ip address of the container as 10.0.3.223. There are no firewalls in action on either host or container. As suggested in several online posts, I have used the following two iptables commands to port forward port 80 on my host to port 80 on the container-

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to 10.0.3.223:80
iptables -A FORWARD -p tcp -d 10.0.3.223 --dport 80 -j ACCEPT

But when I point my browser on another machine on the LAN to the host, I cannot connect to the nginx test page on the container. I know that because I have nginx running on the host with one form of the nginx test page, and nginx running in the container with another form of the nginx test page. The two above port forwarding commands should have made the browser bypass the host port 80 and exposed port 80 on the container, therefore showing me the nginx test page in the container.

What is interesting to me is that when I substitute port 22 for port 80 in the above two commands, I can then ssh from another machine on the network to the container, using the hosts ip address (and the username and password for the container user ubuntu)! In other words, the iptables port forwarding commands worked for port 22 but not for port 80, or so it appears.

Any suggestions about why these two commands don't work for port 80?
Thanks!