'Add to Cart' button fails using 'Display: inline' in in Agile Web Development with Rails (4th edition) -

i cannot make 'add cart' button inline next product price, reason not understand, button appears below product price.

here development settings:

ruby 1.9.3p392

rails 4.0.0.rc2

i following depot project , stuck in iteration d3 author insert button next product price through following css code:

#store .entry form, #store .entry form div { display: inline; } 

and views/store/index.html.erb follow:

<% if notice %> <p id="notice"><%= notice %></p> <% end %>  <h1>your pragmatic catalog</h1>  <% @products.each |product| %>   <div class="entry">     <%= image_tag(product.image_url) %>     <h3><%= product.title %></h3>     <%= sanitize(product.description) %>   <div class="price_line">       <span class="price"><%= number_to_currency(product.price) %></span>       <%= button_to 'add cart' , line_items_path(:product_id => product) %>   </div>   </div> <% end %> 

also have reviewing html rendered google chrome:

<div class="price_line">   <span class="price">$34.95</span>   <form action="/line_items?product_id=4" class="button_to" method="post">   <div><input type="submit" value="add cart" /><input name="authenticity_token"    type="hidden" value="ytcdgb4x1h98dxni0dqqhv4hjfqdusbpmwslll3gehw=" />   </div></form> </div> 

i have tested on google chrome, firefox, ie9 , opera. seems not problem related browser. need can explain weird behavior smartest way solve it. :-)

thanks in advance input.