This layout exercise is created by @byr-gdp , this is an English vrsion translated by me.

All exercises based on the following HTML structure (do not change the HTML structure, or it will lose the meaning of practice), all you need to do is to add css code in layout area to change the layout of the page.

HTML:

<div id="container">
	<div id="header">Header</div>
	<div id="wrapper">
		<div id="content">Content</div>
	</div>
	<div id="navigation">Navigation</div>
	<div id="extra">Extra stuff</div>
	<div id="footer">Footer</div>
</div>

CSS:

/*basic style*/
#container { 
    font-size: 12px; 
    font-family: arial, sans-serif;
}
p { 
    margin: 0 10px 10px;
}
#header {
    height: 80px; 
    background-color: rgb(238,238,238); 
    color: rgb(122,177,36); 
    padding-left: 10px; 
    line-height: 80px; }
#header h1 {
    margin: 0;
}
#navigation {
    background-color: rgb(186,203,253);
}
#extra {
    background-color: rgb(253,133,67);
}
#footer {
    height: 14px;  
    padding:5px 10px 5px 10px; 
    color: #FFF; 
    background-color: #333;
}
#footer p {
    line-height: 14px; 
    margin: 0px;
}

/* layout */

There are three elements: wrapper, navigation and extra

Guide:

1. Set the width of wrapper to 50% and horizontally center the wrapper element.
2. Set width of navigation and extra to 25%, navigation on the left side of wrapper, extra on the right.

Example:

Guide:

1. Exchanges positions of navigation and extra on the basis of exercise 1.

Example:

There are three elements: content, navigation and extra

Guide:

1. Set the wrapper aligned left and width to 50%,
2. Set width of navigation, extra to 25%，arrange them on the right side of content in order.

Example:

Guide:

1. Exchanges positions of navigation and extra on the basis of exercise 2.

Example: