The box “CSS Specifications” lists the different CSS specifications.
Cascading Style Sheets (CSS) represent a major breakthrough in how Web-page designers work by expanding their ability to control the appearance of Web pages, which are the documents that people publish on the Web.
For the first few years after the World Wide Web (the Web) was created in 1990, people who wanted to put pages on the Web had little control over what those pages looked like. In the beginning, authors could only specify structural aspects of their pages (for example, that some piece of text would be a heading or some other piece would be straight text). Also, there were ways to make text bold or italic, among a few other effects, but that's where their control ended.
<%= import('ch01/the_web.html.erb')%> <%= import('ch01/dev_of_the_web.html.erb')%> <%= import('ch01/adding_images.html.erb')%>