PHP Developers

Saturday, August 18, 2012

CSS Box Model

The CSS Box Model

All HTML elements can be considered as boxes. In CSS, the term "box model" is used when talking about design and layout.

The CSS box model is essentially a box that wraps around HTML elements, and it consists of: margins, borders, padding, and the actual content.

The box model allows us to place a border around elements and space elements in relation to other elements.

The image below illustrates the box model:

Explanation of the different parts:

Margin - Clears an area around the border. The margin does not have a background color, it is completely transparent
Border - A border that goes around the padding and content. The border is affected by the background color of the box
Padding - Clears an area around the content. The padding is affected by the background color of the box
Content - The content of the box, where text and images appear

In order to set the width and height of an element correctly in all browsers, you need to know how the box model works.

Width and Height of an Element

Important: When you set the width and height properties of an element with CSS, you just set the width and height of the content area. To calculate the full size of an element, you must also add the padding, borders and margins.

The total width of the element in the example below is 300px:

width:250px;
padding:10px;
border:5px solid gray;
margin:10px;

Let's do the math:
250px (width)
+ 20px (left and right padding)
+ 10px (left and right border)
+ 20px (left and right margin)
= 300px

Assume that you had only 250px of space. Let's make an element with a total width of 250px:

Example

width:220px;
padding:10px;
border:5px solid gray;
margin:0px;

Try it yourself »

The total width of an element should be calculated like this:

Total element width = width + left padding + right padding + left border + right border + left margin + right margin

The total height of an element should be calculated like this:

Total element height = height + top padding + bottom padding + top border + bottom border + top margin + bottom margin

Browsers Compatibility Issue

The example above does not display properly in IE8 and earlier versions.

IE8 and earlier versions includes padding and border in the width, if a DOCTYPE is NOT declared.

To fix this problem, just add a DOCTYPE to the HTML page:

Example

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<style type="text/css">
div.ex
{
width:220px;
padding:10px;
border:5px solid gray;
margin:0px;
}
</style>
</head>

Try it yourself »

Thursday, August 16, 2012

CSS Styling Tables

The look of an HTML table can be greatly improved with CSS:

Company	Contact	Country
Alfreds Futterkiste	Maria Anders	Germany
Berglunds snabbköp	Christina Berglund	Sweden
Centro comercial Moctezuma	Francisco Chang	Mexico
Ernst Handel	Roland Mendel	Austria
Island Trading	Helen Bennett	UK
Königlich Essen	Philip Cramer	Germany
Laughing Bacchus Winecellars	Yoshi Tannamuri	Canada
Magazzini Alimentari Riuniti	Giovanni Rovelli	Italy
North/South	Simon Crowther	UK
Paris spécialités	Marie Bertrand	France
The Big Cheese	Liz Nixon	USA
Vaffeljernet	Palle Ibsen	Denmark

Table Borders

To specify table borders in CSS, use the border property.

The example below specifies a black border for table, th, and td elements:

Example

table, th, td
{
border: 1px solid black;
}

Try it yourself »

Notice that the table in the example above has double borders. This is because both the table and the th/td elements have separate borders.

To display a single border for the table, use the border-collapse property.

Collapse Borders

The border-collapse property sets whether the table borders are collapsed into a single border or separated:

Example

table
{
border-collapse:collapse;
}
table,th, td
{
border: 1px solid black;
}

Try it yourself »

Table Width and Height

Width and height of a table is defined by the width and height properties.

The example below sets the width of the table to 100%, and the height of the th elements to 50px:

Example

table
{
width:100%;
}
th
{
height:50px;
}

Try it yourself »

Table Text Alignment

The text in a table is aligned with the text-align and vertical-align properties.

The text-align property sets the horizontal alignment, like left, right, or center:

Example

td
{
text-align:right;
}

Try it yourself »

The vertical-align property sets the vertical alignment, like top, bottom, or middle:

Example

td
{
height:50px;
vertical-align:bottom;
}

Try it yourself »

Table Padding

To control the space between the border and content in a table, use the padding property on td and th elements:

Example

td
{
padding:15px;
}

Try it yourself »

Table Color

The example below specifies the color of the borders, and the text and background color of th elements:

Example

table, td, th
{
border:1px solid green;
}
th
{
background-color:green;
color:white;
}

Try it yourself »

More Examples

Make a fancy table
This example demonstrates how to create a fancy table.

Set the position of the table caption
This example demonstrates how to position the table caption.

CSS Styling Lists

The CSS list properties allow you to:

Set different list item markers for ordered lists
Set different list item markers for unordered lists
Set an image as the list item marker

List

In HTML, there are two types of lists:

unordered lists - the list items are marked with bullets
ordered lists - the list items are marked with numbers or letters

With CSS, lists can be styled further, and images can be used as the list item marker.

Different List Item Markers

The type of list item marker is specified with the list-style-type property:

Example

ul.a {list-style-type: circle;}
ul.b {list-style-type: square;}

ol.c {list-style-type: upper-roman;}
ol.d {list-style-type: lower-alpha;}

Try it yourself »

Some of the values are for unordered lists, and some for ordered lists.

An Image as The List Item Marker

To specify an image as the list item marker, use the list-style-image property:

Example

ul
{
list-style-image: url('sqpurple.gif');
}

Try it yourself »

The example above does not display equally in all browsers. IE and Opera will display the image-marker a little bit higher than Firefox, Chrome, and Safari.

If you want the image-marker to be placed equally in all browsers, a crossbrowser solution is explained below.

Crossbrowser Solution

The following example displays the image-marker equally in all browsers:

Example

ul
{
list-style-type: none;
padding: 0px;
margin: 0px;
}
ul li
{
background-image: url(sqpurple.gif);
background-repeat: no-repeat;
background-position: 0px 5px;
padding-left: 14px;
}

Try it yourself »

Example explained:

For ul:
- Set the list-style-type to none to remove the list item marker
- Set both padding and margin to 0px (for cross-browser compatibility)
For all li in ul:
- Set the URL of the image, and show it only once (no-repeat)
- Position the image where you want it (left 0px and down 5px)
- Position the text in the list with padding-left

List - Shorthand property

It is also possible to specify all the list properties in one, single property. This is called a shorthand property.

The shorthand property used for lists, is the list-style property:

Example

ul
{
list-style: square url("sqpurple.gif");
}

Try it yourself »

When using the shorthand property, the order of the values are:

list-style-type
list-style-position (for a description, see the CSS properties table below)
list-style-image

It does not matter if one of the values above are missing, as long as the rest are in the specified order.

More Examples

All the different list-item markers for lists
This example demonstrates all the different list-item markers in CSS.

All CSS List Properties

Property	Description
list-style	Sets all the properties for a list in one declaration
list-style-image	Specifies an image as the list-item marker
list-style-position	Specifies if the list-item markers should appear inside or outside the content flow
list-style-type	Specifies the type of list-item marker

CSS Styling Links

Links can be styled in different ways.

Styling Links

Links can be styled with any CSS property (e.g. color, font-family, background, etc.).

Special for links are that they can be styled differently depending on what state they are in.

The four links states are:

a:link - a normal, unvisited link
a:visited - a link the user has visited
a:hover - a link when the user mouses over it
a:active - a link the moment it is clicked

Example

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 */

Try it yourself »

When setting the style for several link states, there are some order rules:

a:hover MUST come after a:link and a:visited
a:active MUST come after a:hover

Common Link Styles

In the example above the link changes color depending on what state it is in.

Lets go through some of the other common ways to style links:

Text Decoration

The text-decoration property is mostly used to remove underlines from links:

Example

a:link {text-decoration:none;}
a:visited {text-decoration:none;}
a:hover {text-decoration:underline;}
a:active {text-decoration:underline;}

Try it yourself »

Background Color

The background-color property specifies the background color for links:

Example

a:link {background-color:#B2FF99;}
a:visited {background-color:#FFFF85;}
a:hover {background-color:#FF704D;}
a:active {background-color:#FF704D;}

Try it yourself »

More Examples

Add different styles to hyperlinks
This example demonstrates how to add other styles to hyperlinks.

Advanced - Create link boxes
This example demonstrates a more advanced example where we combine several CSS properties to display links as boxes.