Introduction to HTML and CSS

Knowledge Sharing Session on
HTML and CSS
Basic HTML and CSS
Ferdous Mahmud Shaon
February 2014

HTML frameset
• Not recommended tag
• Not supported in HTML5

HTML Block vs Inline elements
• Block Elements
– Takes up the full width available, and has a line
break before and after it.
– <p>, <div>, <h1>…. <h6>, <ul>, <ol>, <li>, <table>
• Inline Elements
– Takes up only as much width as necessary, and
does not force line breaks after it.
– <a>, <span>, <img>

HTML Table vs DIV
• Most websites have put their content in multiple columns.
• Multiple columns can be created by using <div> or <table>
elements.
• Even though it is possible to create nice layouts with HTML
tables, tables were designed for presenting tabular data -
NOT as a layout tool!
• The div element is used for grouping HTML elements and
for creating rows and columns with the help of CSS.

HTML <!DOCTYPE>
• Must be the very first thing in HTML document,
even before the <html> tag
• Provides information to the web browser about
what version of HTML the page is written in.
• In HTML 4, the <!DOCTYPE> declaration refers to a
DTD, but in HTML5, the <!DOCTYPE> declaration
does NOT refer to any DTD.

HTML vs XHTML
XHTML
– eXtensible HyperText Markup Language
– Stricter and cleaner version of HTML similar to
XML
– Better cross browser support

HTML vs XHTML
XHTML DOCTYPE
– mandatory
XHTML elements
– must be properly nested
– must always be closed
– must be in lowercase
– must have one root element
XHTML attributes
– names must be in lower case
– values must be quoted
– minimization is forbidden
• <input type="checkbox" checked="checked" />
• <input disabled="disabled" />

SEO friendly HTML
• Meaningful and relevant HTML <title> per page
• Define <meta> description and keywords for each page.
<meta name="description" content="Free Web tutorials on HTML and CSS">
<meta name="keywords" content="HTML, CSS, XML, XHTML, JavaScript">
• Use an <h1> tag for the main headline of the page. It shouldn’t be
more than one in a single page.
• Relevant sub-headlines should use an <h2>…<h6> tags according to
their priority.
• Avoid embedded JS and CSS whenever possible. Try to use external
CSS and JS and if possible minimize them.

New HTML5 Tags
• <canvas> defines graphic drawing using
JavaScript
• <audio> defines sound or music content
• <video> defines video or movie content
• <header> defines a header for the document
or a section
• <nav> defines navigation links in the document

New HTML5 Tags
• <section> defines a section in the document
• <main> defines the main content of a
document
• <article> defines an article in the document
• <footer> defines a footer for the document or
a section
• <figure> defines self-contained content, like
illustrations, diagrams, photos etc.

HTML Style Elements
<font>, <strong>, <b>, <u>, <i>, <em>, <center>

What is CSS?
• Cascading Style Sheets
• Defines how to display HTML elements
• Added to HTML 4.0
• Current version is CSS 2.
• CSS 3 is also released and supported by most
of the browsers.

CSS Box Model – Margin Collapse

CSS Box Model (inline element)

CSS Box Model and Box Sizing
• CSS3 Property
– box-sizing: content-box; /* Default value */
– box-sizing: border-box; /* Grid in Twitter Bootstrap */

CSS Dimension
• height
– Sets the height of an element
• max-height
– Sets the maximum height of an element
• min-height
– Sets the minimum height of an element
• width
– Sets the width of an element
• max-width
– Sets the maximum width of an element
• min-width
– Sets the minimum width of an element

Display and Visibility
• Hiding an Element
– display:none (doesn’t take space)
– visibility:hidden (takes space)
• Styling block / inline HTML Element
– ul.menu li { display:inline; }
– div.data span { display:block; }

Building Menu using HTML & CSS

CSS ‘position’ Property
• static
– default value
– not affected by top, right, bottom, left
• relative
– positioned relative to its normal position
• absolute
– positioned relative to the nearest relatively positioned ancestor
– if no relatively positioned ancestors, then it uses the document body
• fixed
– positioned relative to the viewport
– always stays in the same place even if the page is scrolled.

CSS Relative and Absolute Positioning

Grouping and Nesting Selectors
• Grouping Selectors
– div, p, span {
font-family: "Helvetica Neue", Arial, Helvetica;
}
• Nesting Selectors
– #main .data p { color:blue; }
– .widget.data p { color:blue; }
– #main .data > p { color:blue; }

CSS Pseudo-classes Selectors
• Syntax:
selector:pseudo-class { property:value; }
• Anchor Pseudo-classes
– a:link {color:#FF0000;} /* unvisited link */
– a:visited {color:#00FF00;} /* visited link */
– a:hover {color:#FF00FF;} /* mouse over link */
– a:active {color:#0000FF;} /* selected link */
• First-child Pseudo-class
– ul.menu > li:first-child { margin-left:0; }

CSS Opacity / Transparency
• Transparency
– opacity:0.5;
– filter:alpha(opacity=50); /* For old IEs */
• Cross browser Transparency
.transparent {
/* IE 8 */
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
filter: alpha(opacity=50); /* IE 5-7 */
-moz-opacity: 0.5; /* Netscape */
-khtml-opacity: 0.5; /* Safari 1.x */
opacity: 0.5; /* Good browsers */
}

CSS Image Sprites
• An image sprite is a collection of images put
into a single image.
• Reduces load time and saves bandwidth.
• img.home { width:46px; height:44px;
background:url(img_navsprites.gif) 0 0; }
• img.next { width:43px; height:44px;
background:url(img_navsprites.gif) -91px 0; }

CSS Hacks - IE Detection and
Conditional CSS
• http://www.sitepoint.com/microsoft-drop-ie10-conditional-comments/
• http://msdn.microsoft.com/en-us/library/ms537512%28VS.85%29.aspx

<![if !IE]>
<p>You are using Internet Explorer >=10 or other browsers.</p>
<![endif]>
• Using jQuery for jQuery < 1.9
if (jQuery.browser.msie && jQuery.browser.version < 8) {
// do something
}

CSS Hacks
• IE7 doesn’t understand ‘display: inline-block’
1. display:block;
float:left;
2. display: inline-block;
*display: inline;
zoom: 1;

CSS – major IE6 Problem
• IE6 doesn't support multiple class selectors.
• So when we write,
div.menu.horizontal.widget { color: blue; }
in IE6, the above style is interpreted as:
div.widget { color: blue; }
• This style definition affects all div elements
having widget style class.

Introduction to HTML and CSS

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