(Fast) Introduction to HTML & CSS

(Fast) Introduction to HTML & CSS
Dave Kelly ( @davkell )
for @091Labs

What are HTML & CSS?
HTML structures documents on the web
Tells browser what content is (not what it means)
CSS = presentation (how things look)
JavaScript adds interaction / behaviours
Peanut lifted from http://www.alistapart.com/articles/understandingprogressiveenhancement/
Why separate?
http://www.ambientage.com/blog/091labs : 1

Standards....
define the mark-up you use
tell the browser what to do with it
HTML 4.01 (Don’t use)
xHTML1.0
Frameset (nope)
Transitional (nope)
Strict *
HTML5 (New. Not fully supported / implemented. It’s the future.)
All those defined standards....do all browsers work the same?

Tools
Firefox (wide support for standards)
Firebug (Firefox add-on, Chrome also, but weak). Your best friend with front-end web dev.
Web Developer Toolbar (Firefox add-on)
Validators
HTML: http://validator.w3.org
CSS: http://jigsaw.w3.org
Development environment
Netbeans / Aptana for me.... Your choice (not WYSIWYG!!)
(My) Development process
Firefox -> Webkit (chrome / safari) -> IE8 -> IE7 -> (IE6?)
Browsershots.org

HTML
Made up of “tags” (elements)
<h1>I’m an important heading</h1> (Heading level 1)
<img src=”images/myprofilepic.jpg” alt=”It’s a picture of me!!” /> (Image tag)
Elements can contain plain text, other elements, or both
No state / no logic (Mark-up content only, not programming)
xHTML Strict elements...
must be properly nested
must be closed
must be lower case
attributes must have a value

HTML Tags
Tags are usually paired (e.g..., <h1> and </h1>)
Some elements are “self-closing” e.g. <br /> <img … />
Some elements may include attributes, (additional information that is included inside the start tag).
Every HTML document contains standard tags.
Each document consists of a head and body
The head contains the title (and more…), and
The body contains the actual text that is made up of paragraphs, lists, images, and other elements

Simple HTML Example

Some HTML tag examples
Headings
<h1></h1> , <h2> </h2> …… <h6> </h6>
Paragraph: <p>Some text </p>
Lists
Ordered List <ol> <li>I’m a list item</li></ol>
Unordered list <ul> <li>I’m a list item</li> </ul>
Document Section <div></div> (Important for page layouts!)
Image <img src=“../images/mypic.jpg” alt=“My Picture” title=“It’s me!” />
Links <a href=“http://www.google.com”>Google</a>
Table <table><tr><td>table cell</td></tr>
<tr><td>second row cell</td></tr>
</table>
http://www.ambientage.com/blog/091labs : 4 & 5

Some HTML attribute examples
HTML tags can have attributes => give some more info about the tag
Most can have:
<h1 id=“mainHeading” class=“myHeadingClass” title=“Website title” style=“color: #000000;”>My Heading</h1>

HTML Forms
Forms are used to accept information from the Web page user
Forms can use text boxes, password boxes, check boxes, radio buttons, text areas, drop-down lists, hidden fields, as well as Submit and Clear buttons.
To create a form, the <form></form> element is used.
Forms have 2 basic attributes: action & method, e.g.,
<form name=“myForm” action=“processPage.php” method=“post”>
action = “where’s the data going?”
method = “how’s it getting there? (post vs get)”

HTML Forms

CSS (Cascading Style Sheets)
Handles presentation of web page
It allows document authors to specify the look of a web page (e.g. fonts, spacing, margins,etc.) separately from the structure of the web page (e.g. body, text, links, etc.)
There are 3 ways document styles can be defined:
1. Inline (No!)
2. Internal (ehhhm….no)
External (Yes!)
Concept of the “Cascade”
If a duplicate style is declared, it “cascades” through various layers, each overriding the previous…

The Cascade
The Layers
User agent settings (default browser styles - user is usually able to modify some of these)
Any External (Linked) style sheets (.css file)
Any Internal styles (in head section inside <style> tags)
Inline Styles (in the style attribute of an element)
Each level of style overrides the previous level where duplicate properties are defined

Creating Style Rules
There are 2 pieces to each rule:
The Selector ~ tells the rule what elements it should apply to
The Rule ~ does the formatting of the element
Made up of a property:value pair
The formatting of rules:
Selector { property1: value1;
property2: value2;
propertyN: valueN;
}

Selectors: Match by Element
Easiest selector method is to use an element name, e.g.
p { color: #000000; }
Doing this causes all the tags of that name (i.e.<p>) to be formatted according to the style rule declared.
Possible to do this for multiple elements
h1, h2, h5, p { colour: #ff0000;}

Selectors: Match by Class
Used to display elements of the same type in different ways, e.g.
If the page you’re working with has 2 colours in its background, you need to put light text on the dark background, and dark text on the light background
Classes are defined using a dot (.) and a given name, e.g.
.lightText { color: #ffffff }
To use the class in the document:
<p class=“lightText”>This is white text</p>

Selectors: Match by Identifier
Used to display a specific element in a different way, e.g.
If you need an element on a page presented in a particular way, you can use an Identifier (remember an element’s id attribute is unique to a page)
Identifiers are defined using a hash (#) and a given name, e.g.
#siteTitle{ font-family: ‘Times New Roman’, serif}
To use the class in the document:
<h1 id=“siteTitle”>My Site Name</h1>

Inline Style Rules
…only apply to the current element…
Overrides other styles if duplicates declared (because of the cascade)
Maintenance nightmare

Internal Style Rules
…only apply to the current page…
still slightly nightmarish to maintain

External Style Sheets (.css)
These allow you to…
customise & alter the look of multiple web pages
ensure continuity of design throughout the website
To link an external style sheet to a HTML page use the <link> tag in the <head> section of the document, e.g.

Link Styles
Pseudo-classes are identifiers understood by the browser to apply to a subset of elements, without the element needing to be explicitly tagged with the style

Questions?
Get in touch…
dkelly@ambientage.com
@davkell
linkedin.com/in/davkell
www.ambientage.com
www.davidkelly.ie
Slides & Footnotes
www.ambientage.com/blog/091labs/

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(Fast) Introduction to HTML & CSS

by Dave Kelly on Sep 15, 2010

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