Tag: tutorial

The default positioning for all elements is position:static, which means the element is not positioned and occurs where it normally would in the document.
Normally you wouldn’t specify this unless you needed to override a positioning that had been previously set.

#div-1 {   
position:static;  }

If you specify position:relative, then you can use top or bottom, and left or right to move the element relative to where it would normally occur in the document.

Let’s move div-1 down 20 pixels, and to the left 40 pixels:

#div-1 {   
position:relative;
top:20px;
left:-40px;  }  

Notice the space where div-1 normally would have been if we had not moved it: now it is an empty space. The next element (div-after) did not move when we moved div-1. That’s because div-1 still occupies that original space in the document, even though we have moved it.

It appears that position:relative is not very useful, but it will perform an important task later in this tutorial.

When you specify position:absolute, the element is removed from the document and placed exactly where you tell it to go.

Let’s move div-1a to the top right of the page:

#div-1a {   
position:absolute;   
top:0;   
right:0;   
width:200px;  }  

Notice that this time, since div-1a was removed from the document, the other elements on the page were positioned differently: div-1b, div-1c, and div-after moved up since div-1a was no longer there.

Also notice that div-1a was positioned in the top right corner of the page. It’s nice to be able to position things directly the page, but it’s of limited value.

What I really want is to position div-1a relative to div-1. And that’s where relative position comes back into play.

• There is a bug in the Windows IE browser: if you specify a relative width (like “width:50%”) then the width will be based on the parent element instead of on the positioning element.

If we set relative positioning on div-1, any elements within div-1 will be positioned relative to div-1. Then if we set absolute positioning on div-1a, we can move it to the top right of div-1:

#div-1 {   
position:relative;  }  


#div-1a {   
position:absolute;   
top:0;   
right:0;   
width:200px;  }  

Now we can make a two-column layout using relative and absolute positioning!

#div-1 {   
position:relative;  }  


#div-1a {   
position:absolute;  
 top:0;   
right:0;   
width:200px;  } 


 #div-1b {   
position:absolute;  
 top:0;   
left:0;   
width:200px;  }  

One advantage to using absolute positioning is that we can position the elements in any order on the page, regardless of the order they appear in the HTML. So I put div-1b before div-1a.

But wait – what happened to the other elements? They are being obscured by the absolutely positioned elements. What can we do about that?

For variable height columns, absolute positioning does not work, so let’s come up with another solution.

We can “float” an element to push it as far as possible to the right or to the left, and allow text to wrap around it. This is typically used for images, but we will use it for more complex layout tasks (because it’s the only tool we have).

#div-1a {   
float:left;  
 width:200px;  }  

If we float one column to the left, then also float the second column to the left, they will push up against each other.

#div-1a {  
float:left;   
width:150px;  }  


#div-1b {   
float:left;   
width:150px;  }  

Then after the floating elements we can “clear” the floats to push down the rest of the content.

#div-1a {   
float:left;  
 width:190px;  }  


#div-1b {   
float:left;  
width:190px;  }  


#div-1c {   
clear:both;  }  

Tables existed in HTML for one reason: To display tabular data. But then border=”0″ made it possible for designers to have a grid upon which to lay out images and text. Still the most dominant means of designing visually rich Web sites, the use of tables is now actually interfering with building a better, more accessible, flexible, and functional Web. Find out where the problems stem from, and learn solutions to create transitional or completely table-less layout.

The problem with using tables:

• mixes presentational data in with your content.
  • This makes the file sizes of your pages unnecessarily large, as users must download this presentational data for each page they visit.
  • Bandwidth ain’t free.
• This makes redesigns of existing sites and content extremely labor intensive (and expensive).
• It also makes it extremely hard (and expensive) to maintain visual consistency throughout a site.
• Table-based pages are also much less accessible to users with disabilities and viewers using cell phones and PDAs to access the Web.

Modern browsers are much better at rendering Web standards and we don’t need to use these archaic methods any more.

Instead of nesting tables within tables and filling empty cells with spacer GIFs, we can use much simpler markup and CSS to lay out beautiful sites that are faster to load, easier to redesign, and more accessible to everyone.

By using structural markup in our HTML documents and Cascading Style Sheets to lay out our pages, we can keep the actual content of our pages separated from the way they are presented.

This has several advantages over using tables….

Redesigns are easier and less expensive

By removing presentational markup from your pages, redesigns of existing sites and content is much less labor intensive (and much less expensive). To change the layout of the site, all you need to do is change the style sheets; you do not need to edit the pages themselves at all.

Using Web standards reduces the file sizes of your pages, as users no longer need to download presentational data with each page they visit. The Style sheets that control layout are cached by viewers’ browsers.

Reduced file size means faster loads and lower hosting costs.

Using Web standards also makes it extremely easy to maintain visual consistency throughout a site. Since pages use the same CSS document for their layout, they are all formatted the same.

This strengthens your brand and makes your site more usable.

Using Web standards makes our pages much more accessible to users with disabilities and to viewers using mobile phones and PDAs to access the Web.

Visitors using screen readers (as well as those with slow connections) do not have to wade through countless table cells and spacers to get at the actual content of our pages.

In other words, separating content from the way it is presented makes your content device-independent.

Speaking of accessiblity, minimizing your markup and using header tags properly will also help improve your search engine ranking.

Reducing the ratio of code to content, using keywords in your header tags, and replacing header GIFs with actual text will all help your sites get better search engine results.

A very handy CSS command that exists is the min-width command, whereby you can specify a minimum width for any element. This can be particularly useful for specifying a minimum width for a page.

Unfortunately, IE doesn’t understand this command, so we’ll need to come up with a new way of making this work in this browser. First, we’ll insert a