website_controller.rb
 
   require 'digest-sha2" should be require 'digest/sha2'

register action

   @title = 'Website Example -- Login Page' should be
   @title = 'Website Example -- Register Page'

   Login.save should be login.save

   redirect_to :action -> 'login' should be
   redirect_to :action => 'login'

login action

   dbpw = a[1].passwd should be dbpw = a[0].passwd

   hash = Digest:SHA2.hexdigest(passwd) should be
   hash = Digest::SHA2.hexdigest(passwd)

   if dbpw = hash  should be  if dbpw == hash

   session[isloggedin] = true should be
   session[:isloggedin] = true

index action

   session[isloggedin] = false

logout action

   end is missing at the end of the method.

register.html.erb

   <%= form_tag :action => 'register' %>  should be
   <%= form_tag :action => 'register' do %>

   The <tr> tag after the password_field_tag should be </tr>

   style="r" should be class="r" in the td tags.

   The end table tag is missing at the end of the table.

   <% end %> is missing at the end of the view.

login.html.erb

   <td><%= f.text_field_tag :username, '', should be
   <td><%= text_field_tag :username, '',

   <td><%= password_field_tag password, ''  should be
   <td><%= password_field_tag :password, ''

   <%= link 'Registration Page' :action => 'login' should be
   <%= link_to 'Registration Page', :action => 'register' %>

index.html.erb

   <%= submit_tag 'Logout', :style => 'ctrl' %>  should be
   <%= submit_tag 'Logout', :class => 'ctrl' %>

website.html.erb

   <title>@title</title>  should be
   <title><%= @title %></title>

   The end head and body tags should be switched.

   yield :layout  should be
   <%= yield :layout %>

   The end html tag is missing.

style.css

   font-family; Verdana: size: 110%; }  should be
   font-family: Verdana; font-size: 110%; }

   .ctrl ( fontfamily: Verdana; height: 0.3in; width:2.5in; )
   should be
   .ctrl { font-family: Verdana; height: 0.3in; width:2.5in; }