CSS Introduction (#1)

CSS is the language we use to style a Web page.

What is CSS?

• CSS stands for Cascading Style Sheets
• CSS describes how HTML elements are to be displayed on screen, paper, or in other media
• CSS saves a lot of work. It can control the layout of multiple web pages all at once
• External stylesheets are stored in CSS files

CSS Demo – One HTML Page – Multiple Styles!

Here we will show one HTML page displayed with four different stylesheets.

Why Use CSS?

CSS is used to define styles for your web pages, including the design, layout and variations in display for different devices and screen sizes.

body {
  background-color: lightblue;
}

h1 {
  color: white;
  text-align: center;
}

p {
  font-family: verdana;
  font-size: 20px;
}

CSS Solved a Big Problem

HTML was NEVER intended to contain tags for formatting a web page!

HTML was created to describe the content of a web page, 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 websites, 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 (Swift Games) created CSS.

CSS removed the style formatting from the HTML page!

CSS Saves a Lot of Work!

The style definitions are normally saved in external .css files.

With an external stylesheet file, you can change the look of an entire website by changing just one file!

CSS Syntax (#2)

A CSS rule consists of a selector and a declaration block.

CSS Syntax

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 CSS property name and a value, separated by a colon.

Multiple CSS declarations are separated with semicolons, and declaration blocks are surrounded by curly braces.

p {
  color: red;
  text-align: center;
}

Example Explained

• p is a selector in CSS (it points to the HTML element you want to style: <p>).
• color is a property, and red is the property value
• text-align is a property, and center is the property value

CSS Selectors (#3)

A CSS selector selects the HTML element(s) you want to style.

CSS Selectors

CSS selectors are used to “find” (or select) the HTML elements you want to style.

We can divide CSS selectors into five categories:

• Simple selectors (select elements based on name, id, class)
• Combinator selectors (select elements based on a specific relationship between them)
• Pseudo-class selectors (select elements based on a certain state)
• Pseudo-elements selectors (select and style a part of an element)
• Attribute selectors (select elements based on an attribute or attribute value)

This page will explain the most basic CSS selectors.

The CSS element Selector

The element selector selects HTML elements based on the element name.

p {
  text-align: center;
  color: red;
}

The CSS id Selector

The id selector uses the id attribute of an HTML element to select a specific element.

The id of an element is unique within a page, so the id selector is used to select one unique element!

To select an element with a specific id, write a hash (#) character, followed by the id of the element.

#para1 {
  text-align: center;
  color: red;
}

The CSS class Selector

The class selector selects HTML elements with a specific class attribute.

To select elements with a specific class, write a period (.) character, followed by the class name.

.center {
  text-align: center;
  color: red;
}

You can also specify that only specific HTML elements should be affected by a class.

p.center {
  text-align: center;
  color: red;
}

HTML elements can also refer to more than one class.

<p class="center large">This paragraph refers to two classes.</p>

The CSS Universal Selector

The universal selector (*) selects all HTML elements on the page.

* {
  text-align: center;
  color: blue;
}

The CSS Grouping Selector

The grouping selector selects all the HTML elements with the same style definitions.

Look at the following CSS code (the h1, h2, and p elements have the same style definitions):

h1 {
  text-align: center;
  color: red;
}

h2 {
  text-align: center;
  color: red;
}

p {
  text-align: center;
  color: red;
}

It will be better to group the selectors, to minimize the code.

To group selectors, separate each selector with a comma.

h1, h2, p {
  text-align: center;
  color: red;
}

How To Add CSS (#4)

When a browser reads a style sheet, it will format the HTML document according to the information in the style sheet.

Three Ways to Insert CSS

There are three ways of inserting a style sheet:

• External CSS
• Internal CSS
• Inline CSS

External CSS

With an external style sheet, you can change the look of an entire website by changing just one file!

Each HTML page must include a reference to the external style sheet file inside the <link> element, inside the head section.

<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="mystyle.css">
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

An external style sheet can be written in any text editor, and must be saved with a .css extension.

The external .css file should not contain any HTML tags.

Here is how the “mystyle.css” file looks:

body {
  background-color: lightblue;
}

h1 {
  color: navy;
  margin-left: 20px;
}

Internal CSS

An internal style sheet may be used if one single HTML page has a unique style.

The internal style is defined inside the <style> element, inside the head section.

<!DOCTYPE html>
<html>
<head>
<style>
body {
  background-color: linen;
}

h1 {
  color: maroon;
  margin-left: 40px;
}
</style>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

Inline CSS

An inline style may be used to apply a unique style for a single element.

To use inline styles, add the style attribute to the relevant element. The style attribute can contain any CSS property.

<!DOCTYPE html>
<html>
<body>

<h1 style="color:blue;text-align:center;">This is a heading</h1>
<p style="color:red;">This is a paragraph.</p>

</body>
</html>

Multiple Style Sheets

If some properties have been defined for the same selector (element) in different style sheets, the value from the last read style sheet will be used.

h1 {
  color: navy;
}

h1 {
  color: orange;   
}

<head>
<link rel="stylesheet" type="text/css" href="mystyle.css">
<style>
h1 {
  color: orange;
}
</style>
</head>

<head>
<style>
h1 {
  color: orange;
}
</style>
<link rel="stylesheet" type="text/css" href="mystyle.css">
</head>

Cascading Order

What style will be used when there is more than one style specified for an HTML element?

All the styles in a page will “cascade” into a new “virtual” style sheet by the following rules, where number one has the highest priority:

1. Inline style (inside an HTML element)
2. External and internal style sheets (in the head section)
3. Browser default

So, an inline style has the highest priority, and will override external and internal styles and browser defaults.

CSS Comments (#5)

CSS comments are not displayed in the browser, but they can help document your source code.

CSS Comments

Comments are used to explain the code, and may help when you edit the source code at a later date.

Comments are ignored by browsers.

A CSS comment is placed inside the <style> element, and starts with /* and ends with */:

/* This is a single-line comment */
p {
  color: red;
}

You can add comments wherever you want in the code:

p {
  color: red;  /* Set text color to red */
}

Comments can also span multiple lines:

/* This is
a multi-line
comment */

p {
  color: red;
}

HTML and CSS Comments

From the HTML tutorial, you learned that you can add comments to your HTML source by using the <!--...--> syntax.

In the following example, we use a combination of HTML and CSS comments:

<!DOCTYPE html>
<html>
<head>
<style>
p {
  color: red; /* Set text color to red */
}
</style>
</head>
<body>

<h2>My Heading</h2>

<!-- These paragraphs will be red -->
<p>Hello World!</p>
<p>This paragraph is styled with CSS.</p>
<p>CSS comments are not shown in the output.</p>

</body>
</html>

CSS Backgrounds (#6)

The CSS background properties are used to add background effects for elements.

CSS background-color

The background-color property specifies the background color of an element.

body {
  background-color: lightblue;
}

With CSS, a color is most often specified by:

• a valid color name – like “red”
• a HEX value – like “#ff0000”
• an RGB value – like “rgb(255,0,0)”

Other Elements

You can set the background color for any HTML elements:

h1 {
  background-color: green;
}

div {
  background-color: lightblue;
}

p {
  background-color: yellow;
}

Opacity / Transparency

The opacity property specifies the opacity/transparency of an element. It can take a value from 0.0 – 1.0. The lower value, the more transparent:

opacity 1

opacity 0.1

div {
  background-color: green;
  opacity: 0.3;
}

Transparency using RGBA

If you do not want to apply opacity to child elements, like in our example above, use RGBA color values. The following example sets the opacity for the background color and not the text:

100% opacity

10% opacity

An RGBA color value is specified with: rgba(red, green, blue, alpha). The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (fully opaque).

div {
  background: rgba(0, 128, 0, 0.3) /* Green background with 30% opacity */
}

CSS Background Image (#7)

CSS background-image

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.

body {
  background-image: url("paper.gif");
}

body {
  background-image: url("bgdesert.jpg");
}

The background image can also be set for specific elements, like the <p> element:

p {
  background-image: url("paper.gif");
}

CSS Background Image Repeat (#8)

CSS background-repeat

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 above is repeated only horizontally (background-repeat: repeat-x;), the background will look better:

body {
  background-image: url("gradient_bg.png");
  background-repeat: repeat-x;
}

CSS background-repeat: no-repeat

Showing the background image only once is also 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 placed 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.

CSS background-position

The background-position property is used to specify the position of the background image.

body {
  background-image: url("img_tree.png");
  background-repeat: no-repeat;
  background-position: right top;
}

CSS Background Attachment (#9)

CSS background-attachment

The background-attachment property specifies whether the background image should scroll or be fixed (will not scroll with the rest of the page):

body {
  background-image: url("img_tree.png");
  background-repeat: no-repeat;
  background-position: right top;
  background-attachment: fixed;
}

body {
  background-image: url("img_tree.png");
  background-repeat: no-repeat;
  background-position: right top;
  background-attachment: scroll;
}

CSS Background Shorthand (#10)

CSS background – Shorthand property

To shorten the code, it is also possible to specify all the background properties in one single property. This is called a shorthand property.

Instead of writing:

body {
  background-color: #ffffff;
  background-image: url("img_tree.png");
  background-repeat: no-repeat;
  background-position: right top;
}

You can use the shorthand property background:

body {
  background: #ffffff url("img_tree.png") no-repeat right top;
}

When using the shorthand property the order of the property values is:

• background-color
• background-image
• background-repeat
• background-attachment
• background-position

It does not matter if one of the property values is missing, as long as the other ones are in this order. Note that we do not use the background-attachment property in the examples above, as it does not have a value.

CSS Borders (#11)

The CSS border properties allow you to specify the style, width, and color of an element’s border.

CSS Border Style

The border-style property specifies what kind of border to display.

The following values are allowed:

• dotted – Defines a dotted border
• dashed – Defines a dashed border
• solid – Defines a solid border
• double – Defines a double border
• groove – Defines a 3D grooved border. The effect depends on the border-color value
• ridge – Defines a 3D ridged border. The effect depends on the border-color value
• inset – Defines a 3D inset border. The effect depends on the border-color value
• outset – Defines a 3D outset border. The effect depends on the border-color value
• none – Defines no border
• hidden – Defines a hidden border

The border-style property can have from one to four values (for the top border, right border, bottom border, and the left border).

p.dotted {border-style: dotted;}
p.dashed {border-style: dashed;}
p.solid {border-style: solid;}
p.double {border-style: double;}
p.groove {border-style: groove;}
p.ridge {border-style: ridge;}
p.inset {border-style: inset;}
p.outset {border-style: outset;}
p.none {border-style: none;}
p.hidden {border-style: hidden;}
p.mix {border-style: dotted dashed solid double;}

CSS Border Width (#12)

The border-width property specifies the width of the four borders.

The width can be set as a specific size (in px, pt, cm, em, etc) or by using one of the three pre-defined values: thin, medium, or thick:

p.one {
  border-style: solid;
  border-width: 5px;
}

p.two {
  border-style: solid;
  border-width: medium;
}

p.three {
  border-style: dotted;
  border-width: 2px;
}

p.four {
  border-style: dotted;
  border-width: thick;
}

Specific Side Widths

The border-width property can have from one to four values (for the top border, right border, bottom border, and the left border):

p.one {
  border-style: solid;
  border-width: 5px 20px; /* 5px top and bottom, 20px on the sides */
}

p.two {
  border-style: solid;
  border-width: 20px 5px; /* 20px top and bottom, 5px on the sides */
}

p.three {
  border-style: solid;
  border-width: 25px 10px 4px 35px; /* 25px top, 10px right, 4px bottom and 35px left */
}

CSS Border – Individual Sides (#13)

From the examples on the previous pages, you have seen that it is possible to specify a different border for each side.

In CSS, there are also properties for specifying each of the borders (top, right, bottom, and left):

p {
  border-top-style: dotted;
  border-right-style: solid;
  border-bottom-style: dotted;
  border-left-style: solid;
}

The example above gives the same result as this:

p {
  border-style: dotted solid;
}

So, here is how it works:

If the border-style property has four values:

• border-style: dotted solid double dashed;
  • top border is dotted
  • right border is solid
  • bottom border is double
  • left border is dashed

If the border-style property has three values:

• border-style: dotted solid double;
  • top border is dotted
  • right and left borders are solid
  • bottom border is double

If the border-style property has two values:

• border-style: dotted solid;
  • top and bottom borders are dotted
  • right and left borders are solid

If the border-style property has one value:

• border-style: dotted;
  • all four borders are dotted

/* Four values */
p {
  border-style: dotted solid double dashed;
}

/* Three values */
p {
  border-style: dotted solid double;
}

/* Two values */
p {
  border-style: dotted solid;
}

/* One value */
p {
  border-style: dotted;
}

CSS Border – Shorthand Property

Like you saw in the previous page, there are many properties to consider when dealing with borders.

To shorten the code, it is also possible to specify all the individual border properties in one property.

The border property is a shorthand property for the following individual border properties:

• border-width
• border-style (required)
• border-color

p {
  border: 5px solid red;
}

You can also specify all the individual border properties for just one side:

p {
  border-left: 6px solid red;
}

p {
  border-bottom: 6px solid red;
}

CSS Rounded Borders

The border-radius property is used to add rounded borders to an element:

Normal border

Round border

Rounder border

Roundest border

p {
  border: 2px solid red;
  border-radius: 5px;
}

More Examples

All the top border properties in one declaration
This example demonstrates a shorthand property for setting all of the properties for the top border in one declaration.

Set the style of the bottom border
This example demonstrates how to set the style of the bottom border.

Set the width of the left border
This example demonstrates how to set the width of the left border.

Set the color of the four borders
This example demonstrates how to set the color of the four borders. It can have from one to four colors.

Set the color of the right border
This example demonstrates how to set the color of the right border.

CSS Padding (#14)

Padding is used to create space around an element’s content, inside of any defined borders.

CSS Padding

The CSS padding properties are used to generate space around an element’s content, inside of any defined borders.

With CSS, you have full control over the padding. There are properties for setting the padding for each side of an element (top, right, bottom, and left).

Padding – Individual Sides

CSS has properties for specifying the padding for each side of an element:

• padding-top
• padding-right
• padding-bottom
• padding-left

All the padding properties can have the following values:

• length – specifies a padding in px, pt, cm, etc.
• % – specifies a padding in % of the width of the containing element
• inherit – specifies that the padding should be inherited from the parent element

Note: Negative values are not allowed.

div {
  padding-top: 50px;
  padding-right: 30px;
  padding-bottom: 50px;
  padding-left: 80px;
}

Padding – Shorthand Property

To shorten the code, it is possible to specify all the padding properties in one property.

The padding property is a shorthand property for the following individual padding properties:

• padding-top
• padding-right
• padding-bottom
• padding-left

So, here is how it works:

If the padding property has four values:

• padding: 25px 50px 75px 100px;
  • top padding is 25px
  • right padding is 50px
  • bottom padding is 75px
  • left padding is 100px

div {
  padding: 25px 50px 75px 100px;
}

If the padding property has three values:

• padding: 25px 50px 75px;
  • top padding is 25px
  • right and left paddings are 50px
  • bottom padding is 75px

div {
  padding: 25px 50px 75px;
}

If the padding property has two values:

• padding: 25px 50px;
  • top and bottom paddings are 25px
  • right and left paddings are 50px

div {
  padding: 25px 50px;
}

If the padding property has one value:

• padding: 25px;
  • all four paddings are 25px

div {
  padding: 25px;
}

Padding and Element Width

The CSS width property specifies the width of the element’s content area. The content area is the portion inside the padding, border, and margin of an element.

So, if an element has a specified width, the padding added to that element will be added to the total width of the element. This is often an undesirable result.

div {
  width: 300px;
  padding: 25px;
}

To keep the width at 300px, no matter the amount of padding, you can use the box-sizing property. This causes the element to maintain its actual width; if you increase the padding, the available content space will decrease.

div {
  width: 300px;
  padding: 25px;
  box-sizing: border-box;
}

CSS Height, Width and Max-width (#15)

The CSS height and width properties are used to set the height and width of an element.

The CSS max-width property is used to set the maximum width of an element.

CSS Setting height and width

The height and width properties are used to set the height and width of an element.

The height and width properties do not include padding, borders, or margins. It sets the height/width of the area inside the padding, border, and margin of the element.

CSS height and width Values

The height and width properties may have the following values:

• auto – This is default. The browser calculates the height and width
• length – Defines the height/width in px, cm etc.
• % – Defines the height/width in percent of the containing block
• initial – Sets the height/width to its default value
• inherit – The height/width will be inherited from its parent value

CSS height and width Examples

div {
  height: 200px;
  width: 50%;
  background-color: powderblue;
}

div {
  height: 100px;
  width: 500px;
  background-color: powderblue;
}

Note: Remember that the height and width properties do not include padding, borders, or margins! They set the height/width of the area inside the padding, border, and margin of the element!

Setting max-width

The max-width property is used to set the maximum width of an element.

The max-width can be specified in length values, like px, cm, etc., or in percent (%) of the containing block, or set to none (this is default. Means that there is no maximum width).

The problem with the <div> above occurs when the browser window is smaller than the width of the element (500px). The browser then adds a horizontal scrollbar to the page.

Using max-width instead, in this situation, will improve the browser’s handling of small windows.

Tip: Drag the browser window to smaller than 500px wide, to see the difference between the two divs!

Note: If you for some reason use both the width property and the max-width property on the same element, and the value of the width property is larger than the max-width property; the max-width property will be used (and the width property will be ignored).

div {
  max-width: 500px;
  height: 100px;
  background-color: powderblue;
}

CSS Box Model (#16)

All HTML elements can be considered as boxes.

The CSS Box Model

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 every HTML element. It consists of: margins, borders, padding, and the actual content. The image below illustrates the box model:

Explanation of the different parts:

• Content – The content of the box, where text and images appear
• Padding – Clears an area around the content. The padding is transparent
• Border – A border that goes around the padding and content
• Margin – Clears an area outside the border. The margin is transparent

The box model allows us to add a border around elements, and to define space between elements.

div {
  width: 300px;
  border: 15px solid green;
  padding: 50px;
  margin: 20px;
}

Width and Height of an Element

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

div {
  width: 320px;
  padding: 10px;
  border: 5px solid gray;
  margin: 0;
}

Here is the calculation:

320px (width)
+ 20px (left + right padding)
+ 10px (left + right border)
+ 0px (left + right margin)
= 350px

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

CSS Outline (#17)

An outline is a line drawn outside the element’s border.

CSS Outline

An outline is a line that is drawn around elements, OUTSIDE the borders, to make the element “stand out”.

CSS has the following outline properties:

• outline-style
• outline-color
• outline-width
• outline-offset
• outline

CSS Outline Style

The outline-style property specifies the style of the outline, and can have one of the following values:

• dotted – Defines a dotted outline
• dashed – Defines a dashed outline
• solid – Defines a solid outline
• double – Defines a double outline
• groove – Defines a 3D grooved outline
• ridge – Defines a 3D ridged outline
• inset – Defines a 3D inset outline
• outset – Defines a 3D outset outline
• none – Defines no outline
• hidden – Defines a hidden outline

The following example shows the different outline-style values:

p.dotted {outline-style: dotted;}
p.dashed {outline-style: dashed;}
p.solid {outline-style: solid;}
p.double {outline-style: double;}
p.groove {outline-style: groove;}
p.ridge {outline-style: ridge;}
p.inset {outline-style: inset;}
p.outset {outline-style: outset;}

CSS Text (#18)

CSS has a lot of properties for formatting text.

Text Color

The color property is used to set the color of the text. The color is specified by:

• a color name – like “red”
• a HEX value – like “#ff0000”
• an RGB value – like “rgb(255,0,0)”

The default text color for a page is defined in the body selector.

body {
  color: blue;
}

h1 {
  color: green;
}

Text Color and Background Color

In this example, we define both the background-color property and the color property:

body {
  background-color: lightgrey;
  color: blue;
}

h1 {
  background-color: black;
  color: white;
}

div {
  background-color: blue;
  color: white;
}

CSS Text Alignment and Text Direction

In this chapter you will learn about the following properties:

• text-align
• text-align-last
• direction
• unicode-bidi
• vertical-align

Text Alignment

The text-align property is used to set the horizontal alignment of a text.

A text can be left or right aligned, centered, or justified.

The following example shows center aligned, and left and right aligned text (left alignment is default if text direction is left-to-right, and right alignment is default if text direction is right-to-left):

h1 {
  text-align: center;
}

h2 {
  text-align: left;
}

h3 {
  text-align: right;
}

When the text-align property 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):

div {
  text-align: justify;
}

Text Align Last

The text-align-last property specifies how to align the last line of a text.

p.a {
  text-align-last: right;
}

p.b {
  text-align-last: center;
}

p.c {
  text-align-last: justify;
}

Text Direction

The direction and unicode-bidi properties can be used to change the text direction of an element:

p {
  direction: rtl;
  unicode-bidi: bidi-override;
}

Vertical Alignment

The vertical-align property sets the vertical alignment of an element.

img.a {
  vertical-align: baseline;
}

img.b {
  vertical-align: text-top;
}

img.c {
  vertical-align: text-bottom;
}

img.d {
  vertical-align: sub;
}

img.e {
  vertical-align: super;
}

CSS Text Shadow (#19)

Text Shadow

The text-shadow property adds shadow to text.

In its simplest use, you only specify the horizontal shadow (2px) and the vertical shadow (2px):

Text shadow effect!

h1 {
  text-shadow: 2px 2px;
}

Next, add a color (red) to the shadow:

Text shadow effect!

h1 {
  text-shadow: 2px 2px red;
}

Then, add a blur effect (5px) to the shadow:

Text shadow effect!

h1 {
  text-shadow: 2px 2px 5px red;
}

More Text Shadow Examples

h1 {
  color: white;
  text-shadow: 2px 2px 4px #000000;
}

h1 {
  text-shadow: 0 0 3px #ff0000;
}

h1 {
  text-shadow: 0 0 3px #ff0000, 0 0 5px #0000ff;
}

h1 {
  color: white;
  text-shadow: 1px 1px 2px black, 0 0 25px blue, 0 0 5px darkblue;
}

CSS Fonts (#20)

Choosing the right font for your website is important!

Font Selection is Important

Choosing the right font has a huge impact on how the readers experience a website.

The right font can create a strong identity for your brand.

Using a font that is easy to read is important. The font adds value to your text. It is also important to choose the correct color and text size for the font.

Generic Font Families

In CSS there are five generic font families:

1. Serif fonts have a small stroke at the edges of each letter. They create a sense of formality and elegance.
2. Sans-serif fonts have clean lines (no small strokes attached). They create a modern and minimalistic look.
3. Monospace fonts – here all the letters have the same fixed width. They create a mechanical look.
4. Cursive fonts imitate human handwriting.
5. Fantasy fonts are decorative/playful fonts.

All the different font names belong to one of the generic font families.

Difference Between Serif and Sans-serif Fonts

Some Font Examples

The CSS font-family Property

In CSS, we use the font-family property to specify the font of a text.

Tip: The font-family property should hold several font names as a “fallback” system, to ensure maximum compatibility between browsers/operating systems. 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). The font names should be separated with comma.

.p1 {
  font-family: "Times New Roman", Times, serif;
}

.p2 {
  font-family: Arial, Helvetica, sans-serif;
}

.p3 {
  font-family: "Lucida Console", "Courier New", monospace;
}

CSS Icons (#21)

Icons can easily be added to your HTML page, by using an icon library.

The simplest way to add an icon to your HTML page, is with an icon library, such as Font Awesome.

Add the name of the specified icon class to any inline HTML element (like <i> or <span>).

All the icons in the icon libraries below, are scalable vectors that can be customized with CSS (size, color, shadow, etc.)

Font Awesome Icons

To use the Font Awesome icons, go to fontawesome.com, sign in, and get a code to add in the <head> section of your HTML page:

<script src="https://kit.fontawesome.com/yourcode.js" crossorigin="anonymous"></script>

Note: No downloading or installation is required!

<!DOCTYPE html>
<html>
<head>
<script src="https://kit.fontawesome.com/a076d05399.js" crossorigin="anonymous"></script>
</head>
<body>

<i class="fas fa-cloud"></i>
<i class="fas fa-heart"></i>
<i class="fas fa-car"></i>
<i class="fas fa-file"></i>
<i class="fas fa-bars"></i>

</body>
</html>

Bootstrap Icons

To use the Bootstrap glyphicons, add the following line inside the <head> section of your HTML page:

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

Note: No downloading or installation is required!

Google Icons

To use the Google icons, add the following line inside the <head> section of your HTML page:

<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">

Note: No downloading or installation is required!

<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
</head>
<body>

<i class="material-icons">cloud</i>
<i class="material-icons">favorite</i>
<i class="material-icons">attachment</i>
<i class="material-icons">computer</i>
<i class="material-icons">traffic</i>

</body>
</html>

CSS Links (#22)

With CSS, links can be styled in many different ways.

Text Link Text Link Link Button Link Button

Styling Links

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

a {
  color: hotpink;
}

In addition, links 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

/* unvisited link */
a:link {
  color: red;
}

/* visited link */
a:visited {
  color: green;
}

/* mouse over link */
a:hover {
  color: hotpink;
}

/* selected link */
a:active {
  color: blue;
}

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

Text Decoration

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;
}

Background Color

The background-color property can be used to specify a background color for links:

a:link {
  background-color: yellow;
}

a:visited {
  background-color: cyan;
}

a:hover {
  background-color: lightgreen;
}

a:active {
  background-color: hotpink;
} 

Link Buttons

This example demonstrates a more advanced example where we combine several CSS properties to display links as boxes/buttons:

a:link, a:visited {
  background-color: #f44336;
  color: white;
  padding: 14px 25px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
}

a:hover, a:active {
  background-color: red;
}

More Examples

a.one:link {color: #ff0000;}
a.one:visited {color: #0000ff;}
a.one:hover {color: #ffcc00;}

a.two:link {color: #ff0000;}
a.two:visited {color: #0000ff;}
a.two:hover {font-size: 150%;}

a.three:link {color: #ff0000;}
a.three:visited {color: #0000ff;}
a.three:hover {background: #66ff66;}

a.four:link {color: #ff0000;}
a.four:visited {color: #0000ff;}
a.four:hover {font-family: monospace;}

a.five:link {color: #ff0000; text-decoration: none;}
a.five:visited {color: #0000ff; text-decoration: none;}
a.five:hover {text-decoration: underline;}

a:link, a:visited {
  background-color: white;
  color: black;
  border: 2px solid green;
  padding: 10px 20px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
}

a:hover, a:active {
  background-color: green;
  color: white;
}

<span style="cursor: auto">auto</span><br>
<span style="cursor: crosshair">crosshair</span><br>
<span style="cursor: default">default</span><br>
<span style="cursor: e-resize">e-resize</span><br>
<span style="cursor: help">help</span><br>
<span style="cursor: move">move</span><br>
<span style="cursor: n-resize">n-resize</span><br>
<span style="cursor: ne-resize">ne-resize</span><br>
<span style="cursor: nw-resize">nw-resize</span><br>
<span style="cursor: pointer">pointer</span><br>
<span style="cursor: progress">progress</span><br>
<span style="cursor: s-resize">s-resize</span><br>
<span style="cursor: se-resize">se-resize</span><br>
<span style="cursor: sw-resize">sw-resize</span><br>
<span style="cursor: text">text</span><br>
<span style="cursor: w-resize">w-resize</span><br>
<span style="cursor: wait">wait</span>

CSS Lists (#23)

HTML Lists and CSS List Properties

In HTML, there are two main types of lists:

• unordered lists (<ul>) – the list items are marked with bullets
• ordered lists (<ol>) – the list items are marked with numbers or letters

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
• Add background colors to lists and list items

Different List Item Markers

The list-style-type property specifies the type of list item marker.

The following example shows some of the available list item markers:

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;
}

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

An Image as The List Item Marker

The list-style-image property specifies an image as the list item marker:

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

Position The List Item Markers

The list-style-position property specifies the position of the list-item markers (bullet points).

“list-style-position: outside;” means that the bullet points will be outside the list item. The start of each line of a list item will be aligned vertically. This is default:

• Coffee – A brewed drink prepared from roasted coffee beans…
• Tea
• Coca-cola

“list-style-position: inside;” means that the bullet points will be inside the list item. As it is part of the list item, it will be part of the text and push the text at the start:

• Coffee – A brewed drink prepared from roasted coffee beans…
• Tea
• Coca-cola

ul.a {
  list-style-position: outside;
}

ul.b {
  list-style-position: inside;
}

Remove Default Settings

The list-style-type:none property can also be used to remove the markers/bullets. Note that the list also has default margin and padding. To remove this, add margin:0 and padding:0 to <ul> or <ol>:

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}

List – Shorthand property

The list-style property is a shorthand property. It is used to set all the list properties in one declaration:

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

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

• list-style-type (if a list-style-image is specified, the value of this property will be displayed if the image for some reason cannot be displayed)
• list-style-position (specifies whether the list-item markers should appear inside or outside the content flow)
• list-style-image (specifies an image as the list item marker)

If one of the property values above are missing, the default value for the missing property will be inserted, if any.

Styling List With Colors

We can also style lists with colors, to make them look a little more interesting.

Anything added to the <ol> or <ul> tag, affects the entire list, while properties added to the <li> tag will affect the individual list items:

ol {
  background: #ff9999;
  padding: 20px;
}

ul {
  background: #3399ff;
  padding: 20px;
}

ol li {
  background: #ffe5e5;
  color: darkred;
  padding: 5px;
  margin-left: 35px;
}

ul li {
  background: #cce5ff;
  color: darkblue;
  margin: 5px;
}

CSS Tables (#24)

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

Table Borders

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

The example below specifies a solid border for <table>, <th>, and <td> elements:

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

Full-Width Table

The table above might seem small in some cases. If you need a table that should span the entire screen (full-width), add width: 100% to the <table> element:

table {
  width: 100%;
}

Collapse Table Borders

The border-collapse property sets whether the table borders should be collapsed into a single border:

table {
  border-collapse: collapse;
}

If you only want a border around the table, only specify the border property for <table>:

table {
  border: 1px solid;
}

CSS Table Size (#25)

Table Width and Height

The width and height of a table are 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 70px:

table {
  width: 100%;
}

th {
  height: 70px;
}

To create a table that should only span half the page, use width: 50%:

table {
  width: 50%;
}

CSS Table Style (#26)

Table Padding

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

th, td {
  padding: 15px;
  text-align: left;
}

Horizontal Dividers

Add the border-bottom property to <th> and <td> for horizontal dividers:

th, td {
  border-bottom: 1px solid #ddd;
}

Hoverable Table

Use the :hover selector on <tr> to highlight table rows on mouse over:

tr:hover {background-color: coral;}

Striped Tables

For zebra-striped tables, use the nth-child() selector and add a background-color to all even (or odd) table rows:

tr:nth-child(even) {background-color: #f2f2f2;}

Table Color

The example below specifies the background color and text color of <th> elements:

th {
  background-color: #04AA6D;
  color: white;
}

CSS Layout – The display Property (#27)

The display property is the most important CSS property for controlling layout.

The display Property

The display property specifies if/how an element is displayed.

Every HTML element has a default display value depending on what type of element it is. The default display value for most elements is block or inline.

Click to show panel

Block-level Elements

A block-level element always starts on a new line and takes up the full width available (stretches out to the left and right as far as it can).

Examples of block-level elements:

• <div>

• <h1> - <h6>

• <p>

• <form>

• <header>

• <footer>

• <section>

Inline Elements

An inline element does not start on a new line and only takes up as much width as necessary.

This is an inline <span> element inside a paragraph.

Examples of inline elements:

• <span>

• <a>

• <img>

Display: none;

display: none; is commonly used with JavaScript to hide and show elements without deleting and recreating them. Take a look at our last example on this page if you want to know how this can be achieved.

The <script> element uses display: none; as default.

Override The Default Display Value

As mentioned, every element has a default display value. However, you can override this.

Changing an inline element to a block element, or vice versa, can be useful for making the page look a specific way, and still follow the web standards.

A common example is making inline <li> elements for horizontal menus:

li {
  display: inline;
}

The following example displays <span> elements as block elements:

span {
  display: block;
}

The following example displays <a> elements as block elements:

a {
  display: block;
}

Hide an Element – display:none or visibility:hidden?

Hiding an element can be done by setting the display property to none. The element will be hidden, and the page will be displayed as if the element is not there:

h1.hidden {
  display: none;
}

visibility:hidden; also hides an element.

However, the element will still take up the same space as before. The element will be hidden, but still affect the layout:

h1.hidden {
  visibility: hidden;
}

CSS Layout – width and max-width (#28)

Using width, max-width and margin: auto;

As mentioned in the previous chapter; a block-level element always takes up the full width available (stretches out to the left and right as far as it can).

Setting the width of a block-level element will prevent it from stretching out to the edges of its container. Then, you can set the margins to auto, to horizontally center the element within its container. The element will take up the specified width, and the remaining space will be split equally between the two margins:

Note: The problem with the <div> above occurs when the browser window is smaller than the width of the element. The browser then adds a horizontal scrollbar to the page.

Using max-width instead, in this situation, will improve the browser’s handling of small windows. This is important when making a site usable on small devices:

Tip: Resize the browser window to less than 500px wide, to see the difference between the two divs!

Here is an example of the two divs above:

div.ex1 {
  width: 500px;
  margin: auto;
  border: 3px solid #73AD21;
}

div.ex2 {
  max-width: 500px;
  margin: auto;
  border: 3px solid #73AD21;
}

CSS Layout – The position Property (#29)

The position property specifies the type of positioning method used for an element (static, relative, fixed, absolute or sticky).

The position Property

The position property specifies the type of positioning method used for an element.

There are five different position values:

• static
• relative
• fixed
• absolute
• sticky

Elements are then positioned using the top, bottom, left, and right properties. However, these properties will not work unless the position property is set first. They also work differently depending on the position value.

position: static;

HTML elements are positioned static by default.

Static positioned elements are not affected by the top, bottom, left, and right properties.

An element with position: static; is not positioned in any special way; it is always positioned according to the normal flow of the page:

Here is the CSS that is used:

div.static {
  position: static;
  border: 3px solid #73AD21;
}

position: relative;

An element with position: relative; is positioned relative to its normal position.

Setting the top, right, bottom, and left properties of a relatively-positioned element will cause it to be adjusted away from its normal position. Other content will not be adjusted to fit into any gap left by the element.

Here is the CSS that is used:

div.relative {
  position: relative;
  left: 30px;
  border: 3px solid #73AD21;
}

position: fixed;

An element with position: fixed; is positioned relative to the viewport, which means it always stays in the same place even if the page is scrolled. The top, right, bottom, and left properties are used to position the element.

A fixed element does not leave a gap in the page where it would normally have been located.

Notice the fixed element in the lower-right corner of the page. Here is the CSS that is used:

div.fixed {
  position: fixed;
  bottom: 0;
  right: 0;
  width: 300px;
  border: 3px solid #73AD21;
}

position: absolute;

An element with position: absolute; is positioned relative to the nearest positioned ancestor (instead of positioned relative to the viewport, like fixed).

However; if an absolute positioned element has no positioned ancestors, it uses the document body, and moves along with page scrolling.

Note: Absolute positioned elements are removed from the normal flow, and can overlap elements.

Here is a simple example:

Here is the CSS that is used:

div.relative {
  position: relative;
  width: 400px;
  height: 200px;
  border: 3px solid #73AD21;
}

div.absolute {
  position: absolute;
  top: 80px;
  right: 0;
  width: 200px;
  height: 100px;
  border: 3px solid #73AD21;
}

position: sticky;

An element with position: sticky; is positioned based on the user’s scroll position.

A sticky element toggles between relative and fixed, depending on the scroll position. It is positioned relative until a given offset position is met in the viewport – then it “sticks” in place (like position:fixed).

In this example, the sticky element sticks to the top of the page (top: 0), when you reach its scroll position.

div.sticky {
  position: -webkit-sticky; /* Safari */
  position: sticky;
  top: 0;
  background-color: green;
  border: 2px solid #4CAF50;
}

Positioning Text In an Image

How to position text over an image:

CSS Layout – The z-index Property (#30)

The z-index property specifies the stack order of an element.

The z-index Property

When elements are positioned, they can overlap other elements.

The z-index property specifies the stack order of an element (which element should be placed in front of, or behind, the others).

An element can have a positive or negative stack order:

img {
  position: absolute;
  left: 0px;
  top: 0px;
  z-index: -1;
}

Note: z-index only works on positioned elements (position: absolute, position: relative, position: fixed, or position: sticky) and flex items (elements that are direct children of display: flex elements).

Another z-index Example

<html>
<head>
<style>
.container {
  position: relative;
}

.black-box {
  position: relative;
  z-index: 1;
  border: 2px solid black;
  height: 100px;
  margin: 30px;
}

.gray-box {
  position: absolute;
  z-index: 3;
  background: lightgray;
  height: 60px;
  width: 70%;
  left: 50px;
  top: 50px;
}

.green-box {
  position: absolute;
  z-index: 2;
  background: lightgreen;
  width: 35%;
  left: 270px;
  top: -15px;
  height: 100px;
}
</style>
</head>
<body>

<div class="container">
  <div class="black-box">Black box</div>
  <div class="gray-box">Gray box</div>
  <div class="green-box">Green box</div>
</div>

</body>
</html>

Without z-index

If two positioned elements overlap each other without a z-index specified, the element defined last in the HTML code will be shown on top.

<html>
<head>
<style>
.container {
  position: relative;
}

.black-box {
  position: relative;
  border: 2px solid black;
  height: 100px;
  margin: 30px;
}

.gray-box {
  position: absolute;
  background: lightgray;
  height: 60px;
  width: 70%;
  left: 50px;
  top: 50px;
}

.green-box {
  position: absolute;
  background: lightgreen;
  width: 35%;
  left: 270px;
  top: -15px;
  height: 100px;
}
</style>
</head>
<body>

<div class="container">
  <div class="black-box">Black box</div>
  <div class="gray-box">Gray box</div>
  <div class="green-box">Green box</div>
</div>

</body>
</html>

CSS Layout – float and clear (#31)

The CSS float property specifies how an element should float.

The CSS clear property specifies what elements can float beside the cleared element and on which side.

The float Property

The float property is used for positioning and formatting content e.g. let an image float left to the text in a container.

The float property can have one of the following values:

• left – The element floats to the left of its container
• right – The element floats to the right of its container
• none – The element does not float (will be displayed just where it occurs in the text). This is default
• inherit – The element inherits the float value of its parent

In its simplest use, the float property can be used to wrap text around images.

Example – float: right;

The following example specifies that an image should float to the right in a text:

img {
  float: right;
}

Example – float: left;

The following example specifies that an image should float to the left in a text:

img {
  float: left;
}

Example – No float

In the following example the image will be displayed just where it occurs in the text (float: none;):

img {
  float: none;
}

Example – Float Next To Each Other

Normally div elements will be displayed on top of each other. However, if we use float: left we can let elements float next to each other:

div {
  float: left;
  padding: 15px;
}

.div1 {
  background: red;
}

.div2 {
  background: yellow;
}

.div3 {
  background: green;
}

CSS Layout – clear and clearfix (#32)

The clear Property

When we use the float property, and we want the next element below (not on right or left), we will have to use the clear property.

The clear property specifies what should happen with the element that is next to a floating element.

The clear property can have one of the following values:

• none – The element is not pushed below left or right floated elements. This is default
• left – The element is pushed below left floated elements
• right – The element is pushed below right floated elements
• both – The element is pushed below both left and right floated elements
• inherit – The element inherits the clear value from its parent

When clearing floats, you should match the clear to the float: If an element is floated to the left, then you should clear to the left. Your floated element will continue to float, but the cleared element will appear below it on the web page.

div1 {
  float: left;
}

div2 {
  clear: left;
}

The clearfix Hack

If a floated element is taller than the containing element, it will “overflow” outside of its container. We can then add a clearfix hack to solve this problem:

.clearfix {
  overflow: auto;
}

The overflow: auto clearfix works well as long as you are able to keep control of your margins and padding (else you might see scrollbars). The new, modern clearfix hack however, is safer to use, and the following code is used for most webpages:

.clearfix::after {
  content: "";
  clear: both;
  display: table;
}

CSS Layout – display: inline-block (#33)

The display: inline-block Value

Compared to display: inline, the major difference is that display: inline-block allows to set a width and height on the element.

Also, with display: inline-block, the top and bottom margins/paddings are respected, but with display: inline they are not.

Compared to display: block, the major difference is that display: inline-block does not add a line-break after the element, so the element can sit next to other elements.

The following example shows the different behavior of display: inline, display: inline-block and display: block:

span.a {
  display: inline; /* the default for span */
  width: 100px;
  height: 100px;
  padding: 5px;
  border: 1px solid blue;
  background-color: yellow;
}

span.b {
  display: inline-block;
  width: 100px;
  height: 100px;
  padding: 5px;
  border: 1px solid blue;
  background-color: yellow;
}

span.c {
  display: block;
  width: 100px;
  height: 100px;
  padding: 5px;
  border: 1px solid blue;
  background-color: yellow;
}

Using inline-block to Create Navigation Links

One common use for display: inline-block is to display list items horizontally instead of vertically. The following example creates horizontal navigation links:

.nav {
  background-color: yellow;
  list-style-type: none;
  text-align: center; 
  padding: 0;
  margin: 0;
}

.nav li {
  display: inline-block;
  font-size: 20px;
  padding: 20px;
}

CSS Layout – Horizontal & Vertical Align (#34)

Center Align Elements

To horizontally center a block element (like <div>), use margin: auto;

Setting the width of the element will prevent it from stretching out to the edges of its container.

The element will then take up the specified width, and the remaining space will be split equally between the two margins:

.center {
  margin: auto;
  width: 50%;
  border: 3px solid green;
  padding: 10px;
}

Note: Center aligning has no effect if the width property is not set (or set to 100%).

Center Align Text

To just center the text inside an element, use text-align: center;

.center {
  text-align: center;
  border: 3px solid green;
}

Center an Image

To center an image, set left and right margin to auto and make it into a block element:

img {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 40%;
}

Left and Right Align – Using position

One method for aligning elements is to use position: absolute;:

.right {
  position: absolute;
  right: 0px;
  width: 300px;
  border: 3px solid #73AD21;
  padding: 10px;
}

Note: Absolute positioned elements are removed from the normal flow, and can overlap elements.

Left and Right Align – Using float

Another method for aligning elements is to use the float property:

.right {
  float: right;
  width: 300px;
  border: 3px solid #73AD21;
  padding: 10px;
}

The clearfix Hack

Then we can add the clearfix hack to the containing element to fix this problem:

.clearfix::after {
  content: "";
  clear: both;
  display: table;
}

Center Vertically – Using padding

There are many ways to center an element vertically in CSS. A simple solution is to use top and bottom padding:

.center {
  padding: 70px 0;
  border: 3px solid green;
}

To center both vertically and horizontally, use padding and text-align: center:

.center {
  padding: 70px 0;
  border: 3px solid green;
  text-align: center;
}

Center Vertically – Using line-height

Another trick is to use the line-height property with a value that is equal to the height property:

.center {
  line-height: 200px;
  height: 200px;
  border: 3px solid green;
  text-align: center;
}

/* If the text has multiple lines, add the following: */
.center p {
  line-height: 1.5;
  display: inline-block;
  vertical-align: middle;
}

Center Vertically – Using position & transform

If padding and line-height are not options, another solution is to use positioning and the transform property:

.center {
  height: 200px;
  position: relative;
  border: 3px solid green;
}

.center p {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

Center Vertically – Using Flexbox

You can also use flexbox to center things. Just note that flexbox is not supported in IE10 and earlier versions:

.center {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 200px;
  border: 3px solid green;
}

CSS Image Gallery (#35)

Image Gallery

The following image gallery is created with CSS:

<html>
<head>
<style>
div.gallery {
  margin: 5px;
  border: 1px solid #ccc;
  float: left;
  width: 180px;
}

div.gallery:hover {
  border: 1px solid #777;
}

div.gallery img {
  width: 100%;
  height: auto;
}

div.desc {
  padding: 15px;
  text-align: center;
}
</style>
</head>
<body>

<div class="gallery">
  <a target="_blank" href="img_5terre.jpg">
    <img src="img_5terre.jpg" alt="Cinque Terre" width="600" height="400">
  </a>
  <div class="desc">Add a description of the image here</div>
</div>

<div class="gallery">
  <a target="_blank" href="img_forest.jpg">
    <img src="img_forest.jpg" alt="Forest" width="600" height="400">
  </a>
  <div class="desc">Add a description of the image here</div>
</div>

<div class="gallery">
  <a target="_blank" href="img_lights.jpg">
    <img src="img_lights.jpg" alt="Northern Lights" width="600" height="400">
  </a>
  <div class="desc">Add a description of the image here</div>
</div>

<div class="gallery">
  <a target="_blank" href="img_mountains.jpg">
    <img src="img_mountains.jpg" alt="Mountains" width="600" height="400">
  </a>
  <div class="desc">Add a description of the image here</div>
</div>

</body>
</html>

More Examples

Responsive Image Gallery

How to use CSS media queries to create a responsive image gallery that will look good on desktops, tablets and smart phones.

#home {
  width: 46px;
  height: 44px;
  background: url(img_navsprites.gif) 0 0;
}

#navlist {
  position: relative;
}

#navlist li {
  margin: 0;
  padding: 0;
  list-style: none;
  position: absolute;
  top: 0;
}

#navlist li, #navlist a {
  height: 44px;
  display: block;
}

#home {
  left: 0px;
  width: 46px;
  background: url('img_navsprites.gif') 0 0;
}

#prev {
  left: 63px;
  width: 43px;
  background: url('img_navsprites.gif') -47px 0;
}

#next {
  left: 129px;
  width: 43px;
  background: url('img_navsprites.gif') -91px 0;
}

#home a:hover {
  background: url('img_navsprites_hover.gif') 0 -45px;
}

#prev a:hover {
  background: url('img_navsprites_hover.gif') -47px -45px;
}

#next a:hover {
  background: url('img_navsprites_hover.gif') -91px -45px;
}

CSS Website Layout (#37)

Website Layout

A website is often divided into headers, menus, content and a footer:

There are tons of different layout designs to choose from. However, the structure above, is one of the most common, and we will take a closer look at it in this tutorial.

Header

A header is usually located at the top of the website (or right below a top navigation menu). It often contains a logo or the website name:

.header {
  background-color: #F1F1F1;
  text-align: center;
  padding: 20px;
}

Navigation Bar

A navigation bar contains a list of links to help visitors navigating through your website:

/* The navbar container */
.topnav {
  overflow: hidden;
  background-color: #333;
}

/* Navbar links */
.topnav a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

/* Links - change color on hover */
.topnav a:hover {
  background-color: #ddd;
  color: black;
}

Content

The layout in this section, often depends on the target users. The most common layout is one (or combining them) of the following:

• 1-column (often used for mobile browsers)
• 2-column (often used for tablets and laptops)
• 3-column layout (only used for desktops)

We will create a 3-column layout, and change it to a 1-column layout on smaller screens:

/* Create three equal columns that float next to each other */
.column {
  float: left;
  width: 33.33%;
}

/* Clear floats after the columns */
.row:after {
  content: "";
  display: table;
  clear: both;
}

/* Responsive layout - makes the three columns stack on top of each other instead of next to each other on smaller screens (600px wide or less) */
@media screen and (max-width: 600px) {
  .column {
    width: 100%;
  }
}

Unequal Columns

The main content is the biggest and the most important part of your site.

It is common with unequal column widths, so that most of the space is reserved for the main content. The side content (if any) is often used as an alternative navigation or to specify information relevant to the main content. Change the widths as you like, only remember that it should add up to 100% in total:

.column {
  float: left;
}

/* Left and right column */
.column.side {
  width: 25%;
}

/* Middle column */
.column.middle {
  width: 50%;
}

/* Responsive layout - makes the three columns stack on top of each other instead of next to each other */
@media screen and (max-width: 600px) {
  .column.side, .column.middle {
    width: 100%;
  }
}

Footer

The footer is placed at the bottom of your page. It often contains information like copyright and contact info:

.footer {
  background-color: #F1F1F1;
  text-align: center;
  padding: 10px;
}

CSS Math Functions (#38)

The CSS math functions allow mathematical expressions to be used as property values. Here, we will explain the calc(), max() and min() functions.

The calc() Function

The calc() function performs a calculation to be used as the property value.

CSS Syntax

Let us look at an example:

#div1 {
  position: absolute;
  left: 50px;
  width: calc(100% - 100px);
  border: 1px solid black;
  background-color: yellow;
  padding: 5px;
}

The max() Function

The max() function uses the largest value, from a comma-separated list of values, as the property value.

CSS Syntax

Let us look at an example:

#div1 {
  background-color: yellow;
  height: 100px;
  width: max(50%, 300px);
}

The min() Function

The min() function uses the smallest value, from a comma-separated list of values, as the property value.

CSS Syntax

Let us look at an example:

#div1 {
  background-color: yellow;
  height: 100px;
  width: min(50%, 300px);
}

All CSS Math Functions