Before you continue you should have a basic understanding of the following:
If you want to study these subjects first, find the tutorials on our Home page.
An HTML document can be displayed with different styles: See how it works
HTML was never intended to contain tags for formatting a document.
HTML was intended to define the content of a document, like:
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
When tags like <font>, and color attributes were added to the HTML 3.2 specification, it started a nightmare for web developers. Development of large web sites, where fonts and color information were added to every single page, became a long and expensive process.
To solve this problem, the World Wide Web Consortium (W3C) created CSS.
In HTML 4.0, all formatting could be removed from the HTML document, and stored in a separate CSS file.
All browsers support CSS today.
CSS defines HOW HTML elements are to be displayed.
Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in a Web site, just by editing one single file!
A CSS rule set consists of a selector and a declaration block:
The selector points to the HTML element you want to style.
The declaration block contains one or more declarations separated by semicolons.
Each declaration includes a property name and a value, separated by a colon.
A CSS declaration always ends with a semicolon, and declaration groups are surrounded by curly braces:
p {color:red;text-align:center;}
To make the CSS code more readable, you can put one declaration on each line, like this:
p {
color: red;
text-align: center;
}
Comments are used to explain your code, and may help you when you edit the source code at a later date. Comments are ignored by browsers.
A CSS comment starts with /* and ends with */. Comments can also span multiple lines:
p {
color: red;
/* This is a single-line comment */
text-align: center;
}
/* This is
a multi-line
comment */
CSS selectors allow you to select and manipulate HTML element(s).
CSS selectors are used to "find" (or select) HTML elements based on their id, classes, types, attributes, values of attributes and much more.
The element selector selects elements based on the element name.
You can select all <p> elements on a page like this: (all <p> elements will be center-aligned, with a red text color)
p {
text-align: center;
color: red;
}
The id selector uses the id attribute of an HTML tag to find the specific element.
An id should be unique within a page, so you should use the id selector when you want to find a single, unique element.
To find an element with a specific id, write a hash character, followed by the id of the element.
The style rule below will be applied to the HTML element with id="para1":
#para1 {
text-align: center;
color: red;
}
|
Do NOT start an ID name with a number! |
The class selector finds elements with the specific class.
The class selector uses the HTML class attribute.
To find elements with a specific class, write a period character, followed by the name of the class:
In the example below, all HTML elements with class="center" will be center-aligned:
.center {
text-align: center;
color: red;
}
You can also specify that only specific HTML elements should be affected by a class.
In the example below, all p elements with class="center" will be center-aligned:
p.center {
text-align: center;
color: red;
}
|
Do NOT start a class name with a number! |
In style sheets there are often elements with the same style:
h1 {
text-align: center;
color: red;
}
h2 {
text-align: center;
color: red;
}
p {
text-align: center;
color: red;
}
To minimize the code, you can group selectors.
To group selectors, separate each selector with a comma.
In the example below we have grouped the selectors from the code above:
h1, h2, p {
text-align: center;
color: red;
}
There are three ways of inserting a style sheet:
An external style sheet is ideal when the style is applied to many pages. With an external style sheet, you can change the look of an entire Web site by changing just one file.
Each page must include a link to the style sheet with the <link> tag. The <link> tag goes inside the head section:
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css">
</head>
An external style sheet can be written in any text editor. The file should not contain any html tags. The style sheet file must be saved with a .css extension. An example of a style sheet file is shown below:
"myStyle.css":
body {
background-color: lightblue;
}
h1 {
color: navy;
margin-left: 20px;
}
|
Do not add a space between the property value and the unit (such as margin-left: 20 px;). The correct way is: margin-left: 20px; |
An internal style sheet should be used when a single document has a unique style. You define internal styles in the head section of an HTML page, inside the <style> tag, like this:
<head>
<style>
body {
background-color: linen;
}
h1 {
color: maroon;
margin-left: 40px;
}
</style>
</head>
An inline style loses many of the advantages of a style sheet (by mixing content with presentation). Use this method sparingly!
To use inline styles, add the style attribute to the relevant tag. The style attribute can contain any CSS property. The example shows how to change the color and the left margin of a h1 element:
<h1 style="color:blue;margin-left:30px;">This is a heading.</h1>
If some properties have been set for the same selector in different style sheets, the values will be inherited from the more specific style sheet.
For example, assume that an external style sheet has the following properties for the h1 selector:
h1 {
color: navy;
margin-left: 20px;
}
then, assume that an internal style sheet also has the following property for the h1 selector:
h1 {
color: orange;
}
If the page with the internal style sheet also links to the external style sheet the properties for the h1 element will be:
color: orange;
margin-left: 20px;
The left margin is inherited from the external style sheet and the color is replaced by the internal style sheet.
Styles can be specified:
Tip: Even multiple external style sheets can be referenced inside a single HTML document.
What style will be used when there is more than one style specified for an HTML element?
Generally speaking we can say that all the styles will "cascade" into a new "virtual" style sheet by the following rules, where number four has the highest priority:
So, an inline style (inside an HTML element) has the highest priority, which means that it will override a style defined inside the <head> tag, or in an external style sheet, or in a browser (a default value).
|
Note: If the link to the external style sheet is placed after the internal style sheet in HTML <head>, the external style sheet will override the internal style sheet! |
The background-color property specifies the background color of an element.
The background color of a page is defined in the body selector:
body {
background-color: #b0c4de;
}
With CSS, a color is most often specified by:
Look at CSS Color Values for a complete list of possible color values.
In the example below, the h1, p, and div elements have different background colors:
h1 {
background-color: #6495ed;
}
p {
background-color: #e0ffff;
}
div {
background-color: #b0c4de;
}
The background-image property specifies an image to use as the background of an element.
By default, the image is repeated so it covers the entire element.
The background image for a page can be set like this:
body {
background-image: url("paper.gif");
}
Below is an example of a bad combination of text and background image. The text is almost not readable:
body {
background-image: url("bgdesert.jpg");
}
By default, the background-image property repeats an image both horizontally and vertically.
Some images should be repeated only horizontally or vertically, or they will look strange, like this:
body {
background-image: url("gradient_bg.png");
}
If the image is repeated only horizontally (repeat-x), the background will look better:
body {
background-image: url("gradient_bg.png");
background-repeat: repeat-x;
}
|
Note: When using a background image, use an image that does not disturb the text. |
Showing the image only once is specified by the background-repeat property:
body {
background-image: url("img_tree.png");
background-repeat: no-repeat;
}
In the example above, the background image is shown in the same place as the text. We want to change the position of the image, so that it does not disturb the text too much.
The position of the image is specified by the background-position property:
body {
background-image: url("img_tree.png");
background-repeat: no-repeat;
background-position: right top;
}
As you can see from the examples above, there are many properties to consider when dealing with backgrounds.
To shorten the code, it is also possible to specify all the properties in one single property. This is called a shorthand property.
The shorthand property for background is simply "background":
body {
background: #ffffff url("img_tree.png") no-repeat right top;
}
When using the shorthand property the order of the property values is:
It does not matter if one of the property values is missing, as long as the ones that are present are in this order.
This example uses more advanced CSS. Take a look: Advanced example
How to set a fixed background image
This example demonstrates how to set a fixed background image. The image will not scroll with the rest of the page.
|
Property |
Description |
|
Sets all the background properties in one declaration |
|
|
Sets whether a background image is fixed or scrolls with the rest of the page |
|
|
Sets the background color of an element |
|
|
Sets the background image for an element |
|
|
Sets the starting position of a background image |
|
|
Sets how a background image will be repeated |
The color property is used to set the color of the text.
With CSS, a color is most often specified by:
Look at CSS Color Values for a complete list of possible color values.
The default color for a page is defined in the body selector.
body {
color: blue;
}
h1 {
color: #00ff00;
}
h2 {
color: rgb(255,0,0);
}
|
Note: For W3C compliant CSS: If you define the color property, you must also define the background-color property. |
The text-align property is used to set the horizontal alignment of a text.
Text can be centered, or aligned to the left or right, or justified.
When text-align is set to "justify", each line is stretched so that every line has equal width, and the left and right margins are straight (like in magazines and newspapers).
h1 {
text-align: center;
}
p.date {
text-align: right;
}
p.main {
text-align: justify;
}
The text-decoration property is used to set or remove decorations from text.
The text-decoration property is mostly used to remove underlines from links for design purposes:
a {
text-decoration: none;
}
It can also be used to decorate text:
h1 {
text-decoration: overline;
}
h2 {
text-decoration: line-through;
}
h3 {
text-decoration: underline;
}
|
Note: It is not recommended to underline text that is not a link, as this often confuses users. |
The text-transform property is used to specify uppercase and lowercase letters in a text.
It can be used to turn everything into uppercase or lowercase letters, or capitalize the first letter of each word.
p.uppercase {
text-transform: uppercase;
}
p.lowercase {
text-transform: lowercase;
}
p.capitalize {
text-transform: capitalize;
}
The text-indent property is used to specify the indentation of the first line of a text.
p {
text-indent: 50px;
}
Specify the space between characters
This example demonstrates how to increase or decrease the space between characters.
Specify the space between lines
This example demonstrates how to specify the space between the lines in a paragraph.
Set the text direction of an element
This example demonstrates how to change the text direction of an element.
Increase the white space between words
This example demonstrates how to increase the white space between words in a paragraph.
Disable text wrapping inside an element
This example demonstrates how to disable text wrapping inside an element.
Vertical alignment of an image
This example demonstrates how to set the vertical align of an image in a text.
Add shadow to text
This example demonstrates how to add shadow to text.
|
Property |
Description |
|
Sets the color of text |
|
|
Specifies the text direction/writing direction |
|
|
Increases or decreases the space between characters in a text |
|
|
Sets the line height |
|
|
Specifies the horizontal alignment of text |
|
|
Specifies the decoration added to text |
|
|
Specifies the indentation of the first line in a text-block |
|
|
Specifies the shadow effect added to text |
|
|
Controls the capitalization of text |
|
|
Used together with the direction property to set or return whether the text should be overridden to support multiple languages in the same document |
|
|
Sets the vertical alignment of an element |
|
|
Specifies how white-space inside an element is handled |
|
|
Increases or decreases the space between words in a text |
In CSS, there are two types of font family names:
|
Generic family |
Font family |
Description |
|
Serif |
Times New Roman |
Serif fonts have small lines at the ends on some characters |
|
Sans-serif |
Arial |
"Sans" means without - these fonts do not have the lines at the ends of characters |
|
Monospace |
Courier New |
All monospace characters have the same width |
|
Note: On computer screens, sans-serif fonts are considered easier to read than serif fonts. |
The font family of a text is set with the font-family property.
The font-family property should hold several font names as a "fallback" system. If the browser does not support the first font, it tries the next font.
Start with the font you want, and end with a generic family, to let the browser pick a similar font in the generic family, if no other fonts are available.
Note: If the name of a font family is more than one word, it must be in quotation marks, like: "Times New Roman".
More than one font family is specified in a comma-separated list:
p {
font-family: "Times New Roman", Times, serif;
}
For more commonly used font combinations, look at our Web Safe Font Combinations.
The font-style property is mostly used to specify italic text.
This property has three values:
p.normal {
font-style: normal;
}
p.italic {
font-style: italic;
}
p.oblique {
font-style: oblique;
}
The font-size property sets the size of the text.
Being able to manage the text size is important in web design. However, you should not use font size adjustments to make paragraphs look like headings, or headings look like paragraphs.
Always use the proper HTML tags, like <h1> - <h6> for headings and <p> for paragraphs.
The font-size value can be an absolute, or relative size.
Absolute size:
Relative size:
|
Note: If you do not specify a font size, the default size for normal text, like paragraphs, is 16px (16px=1em). |
Setting the text size with pixels gives you full control over the text size:
h1 {
font-size: 40px;
}
h2 {
font-size: 30px;
}
p {
font-size: 14px;
}
Tip: However, you can still use the zoom tool to resize the entire page.
To allow users to resize the text (in the browser menu), many developers use em instead of pixels.
The em size unit is recommended by the W3C.
1em is equal to the current font size. The default text size in browsers is 16px. So, the default size of 1em is 16px.
The size can be calculated from pixels to em using this formula: pixels/16=em
h1 {
font-size: 2.5em; /* 40px/16=2.5em */
}
h2 {
font-size: 1.875em; /* 30px/16=1.875em */
}
p {
font-size: 0.875em; /* 14px/16=0.875em */
}
In the example above, the text size in em is the same as the previous example in pixels. However, with the em size, it is possible to adjust the text size in all browsers.
Unfortunately, there is still a problem with older versions of IE. The text becomes larger than it should when made larger, and smaller than it should when made smaller.
The solution that works in all browsers, is to set a default font-size in percent for the <body> element:
body {
font-size: 100%;
}
h1 {
font-size: 2.5em;
}
h2 {
font-size: 1.875em;
}
p {
font-size: 0.875em;
}
Our code now works great! It shows the same text size in all browsers, and allows all browsers to zoom or resize the text!
Set the boldness of the font
This example demonstrates how to set the boldness of a font.
Set the variant of the font
This example demonstrates how to set the variant of a font.
All the font properties in one declaration
This example demonstrates how to use the shorthand property for setting all of the font properties in one declaration.
|
Property |
Description |
|
Sets all the font properties in one declaration |
|
|
Specifies the font family for text |
|
|
Specifies the font size of text |
|
|
Specifies the font style for text |
|
|
Specifies whether or not a text should be displayed in a small-caps font |
|
|
Specifies the weight of a font |
Links can be styled with any CSS property (e.g. color, font-family, background, etc.).
In addition, links can be styled differently depending on what state they are in.
The four links states are:
/* unvisited link */
a:link {
color: #FF0000;
}
/* visited link */
a:visited {
color: #00FF00;
}
/* mouse over link */
a:hover {
color: #FF00FF;
}
/* selected link */
a:active {
color: #0000FF;
}
When setting the style for several link states, there are some order rules:
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:
The text-decoration property is mostly used to remove underlines from links:
a:link {
text-decoration: none;
}
a:visited {
text-decoration: none;
}
a:hover {
text-decoration: underline;
}
a:active {
text-decoration: underline;
}
The background-color property specifies the background color for links:
a:link {
background-color: #B2FF99;
}
a:visited {
background-color: #FFFF85;
}
a:hover {
background-color: #FF704D;
}
a:active {
background-color: #FF704D;
}
In HTML, there are two types of lists:
With CSS, lists can be styled further, and images can be used as the list item marker.
The type of list item marker is specified with the list-style-type property:
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;
}
Some of the values are for unordered lists, and some for ordered lists.
To specify an image as the list item marker, use the list-style-image property:
ul {
list-style-image: url('sqpurple.gif');
}
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.
The following example displays the image-marker equally in all browsers:
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;
}
Example explained:
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:
ul {
list-style: square url("sqpurple.gif");
}
When using the shorthand property, the order of the values are:
It does not matter if one of the values above are missing, as long as the rest are in the specified order.
All the different list-item markers for lists
This example demonstrates all the different list-item markers in CSS.
|
Property |
Description |
|
Sets all the properties for a list in one declaration |
|
|
Specifies an image as the list-item marker |
|
|
Specifies if the list-item markers should appear inside or outside the content flow |
|
|
Specifies the type of list-item marker |
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 |
To specify table borders in CSS, use the border property.
The example below specifies a black border for table, th, and td elements:
table, th, td {
border: 1px solid black;
}
Notice tha