2. What isn’t CSS
A programming language
It lacks variables, logic, operators, etc.
A markup language
It contains no “data” or “content”
A standard
(It’s a specification and no one agrees)
3. What is CSS
A method to style any XML
Presentation (not content)
Universally dis-agreed upon
Inheritance based, so conceptually similar as
subclassing in OOP
4. CSS 1 & 2 & 3
Three major “versions” of CSS
Completely different levels of implementation across
browsers.
CSS 1: 1996
CSS 2: 1998
CSS 3: Probably never.
11. Cascading
xml is hierarchical so css is hierarchical.
Styles applied to parent elements cascade to their
children.
Styles applied at the most general level cascade to all
elements that fit that general level.
12. Cascading
<html>
<head>
<title>A first cascade</title>
<style type="text/css">
p {
font-size: 36px;
color: red;
background: yellow;
}
</style>
</head>
<body>
This is body
<br />
<p>This is a default styled paragraph</p>
<p style="font-size: 24px;">This is 24px
paragraph</p>
<br />
This is more default body
<br />
</body>
</html>
13. So what’s this OOP
OPP has inheritance.
In object-oriented programming, inheritance is a way to
form new classes (instances of which are called
objects) using classes that have already been defined.
The inheritance concept was invented in 1967 for
Simula.
14. That’s not OOP
Type selectors are basically super classes
ID selectors are like instances of a class
Class selectors are like modules
15. Box Model
IE 6 is broken
Almost all other
browsers follow this
Width/Height is
cumulative
