我目前正在通过“使用 Rails 进行敏捷 Web 开发”学习 ruby on rails，但遇到了一个无法修复的错误。到目前为止，我只做了一些基本的操作。我使用类似于此的命令创建了一个脚手架：
rails generate scaffold Product title:string description:text image_url:string price:decimal
然后我耙了一下：
rake db:migrate
运行后，我进入 db/seeds.db 文件并用以下数据填充这个新创建的表：
Product.delete_all
Product.create(:title => 'Web Design for Developers',
:description =>
%{<p>
<em>Web Design for Developers</em> will show you how to make your
web-based application look professionally designed. We'll help you
learn how to pick the right colors and fonts, avoid costly interface
and accessibility mistakes -- your application will really come alive.
We'll also walk you through some common Photoshop and CSS techniques
and work through a web site redesign, taking a new design from concept
all the way to implementation.
</p>},
:image_url => '/images/rails.png',
:price => 42.95)
# . . .
Product.create(:title => 'Programming Ruby 1.9',
:description =>
%{<p>
Ruby is the fastest growing and most exciting dynamic language
out there. If you need to get working programs delivered fast,
you should add Ruby to your toolbox.
</p>},
:image_url => '/images/rails.png',
:price => 49.50)
# . . .
Product.create(:title => 'Rails Test Prescriptions',
:description =>
%{<p>
<em>Rails Test Prescriptions</em> is a comprehensive guide to testing
Rails applications, covering Test-Driven Development from both a
theoretical perspective (why to test) and from a practical perspective
(how to test effectively). It covers the core Rails testing tools and
procedures for Rails 2 and Rails 3, and introduces popular add-ons,
including Cucumber, Shoulda, Machinist, Mocha, and Rcov.
</p>},
:image_url => '/images/rails.png',
:price => 43.75)
我再次收集了这些数据：
rake db:seed
这一切都完成后，我加载了 localhost:3000/products 并且一切正常。然而，这本书想添加一些 CSS 代码来让事情看起来更好一些。一旦我添加了 CSS（完全按照书中的内容），当我加载 localhost:3000/products 时出现错误（错误： http: //postimage.org/image/3qfpta4w7/）。我认为我的错误与我的 CSS 有关，但我不知道该怎么做。这是我的CSS：
.products {
table {
border-collapse: collapse;
}
table tr td {
padding: 5px;
vertical-align: top;
}
.list_image {
width: 60px;
height: 70px;
}
.list_description {
width: 60%;
dl {
margin: 0;
}
dt {
color: #244;
font-weight: bold;
font-size: larger;
}
dd {
margin: 0;
}
}
.list_actions {
font-size: x-small;
text-align: right;
padding-left: 1em;
}
.list_line_even {
background: #e0f8f8;
}
.list_line_odd {
background: #f8b0f8;
}
}
我尝试过改变几件事，但现在成功随之而来。对此的任何和所有输入将不胜感激。（命名您最喜欢的 Rails 书籍以供学习的 PS 奖励积分）。