Location of index.html for jupyterhub

I have installed jupyterhub to Ubuntu linux
when I access http://localhost/ it will automatically forwarded to

when can I find login page? thanks in advance.

JupyterHub uses Tornado.
The login handler is defined in

thank lot, I installed the TLJH in ubuntu, where is the config file located for configure the entry page of TLJH?

the TLJH is installed in /opt/TLJH


    <meta charset="utf-8">

    <meta http-equiv="X-UA- ...

would you tell me where is this page located?

I found this page. it is page.html located inside of template.