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I was recently asked about CSS on the killersites web design forum and liking
what I wrote, I decided to use the post here to begin this article.
CSS is the acronym for: ‘Cascading Style Sheets’. CSS is an extension
to basic HTML that allows you to style your web pages. An example of a style
change would be to make words bold. In standard HTML you would use the <b>
tag like so:
<b>make me bold</b>
This works fine and there is nothing wrong with it per se except that now if
you wanted to say change all you text that you initially made bold to underlined,
you would have to go to every spot in the page and change the tag.
Another disadvantage can be found in this example: say you wanted to make the
above text bold, make the font style Verdanna and change its color to red you
would need a lot of code wrapped around the text:
<font color="#FF0000" face="Verdana, Arial, Helvetica, sans-serif"><strong>This
is text</strong></font>
This is verbose and contributes to making you HTML messy. With CSS you can
create a custom style elsewhere and set all its properties, give it a unique
name and then ‘tag’ your HTML to apply these stylistic properties:
<p class="myNewStyle">My CSS styled text</p>
And in between the <head></head> tags at the top of your web page
you would insert this CSS code that defines the style we just applied:
<style type="text/css">
<!--
.myNewStyle {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-weight: bold;
color: #FF0000;
}
-->
</style>
In the above example we include the style sheet code inline, or in other words,
in the page. This is fine for smaller projects or in situations where the styles
you’re defining will only be used in a single page.
There are many times when you will be applying your styles to many pages and
it would be a hassle to have to copy and paste you CSS code into each page.
Besides the fact that you will be cluttering up your page with the same CSS
code, you also find yourself having to edit each of these pages if you want
to make a style change. Like with JavaScript, you can define/create you CSS
style in a separate file and then link it to the page you want to apply the
code to:
<link href="myFirstStyleSheet.css" rel="stylesheet"
type="text/css">
The above line of code links your external style sheet called ‘myFirstStyleSheet.css’
to the HTML document. You place this code in between the <head> </head>
tags in your web page.
To create an external style sheet all you need to do is create a simple text
document (on windows you simply right-click and select new -> text document)
and then change it from a file type .txt to .css. You can change the file type
by just changing the file names extension. The file name’s extension on
windows tells the computer what kind of file it is and allows the computer to
determine how to handle the file when for example you try to open it.
You probably guessed it; CSS files are just specially formatted text files,
and much in the same way HTML pages are. There is nothing special or different
in the file itself, rather it is the contents of the file that make an HTML
document and a CSS page what they are.
When working with a external CSS document there are a couple of points to remember:
1. You don’t add these tags in the CSS page itself as you would if you
embedded the CSS code in your HTML:
<style type="text/css">
</style>
Since the link in your web page connecting the CSS page to your HTML page says
that you are linking to a CSS page, you don’t need to declare that the
code in the page is CSS. That is what the above tags do. Instead you would just
add your CSS code directly to the page:
.myNewStyle {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-weight: bold;
color: #FF0000;
}
.my2ndNewStyle {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-weight: bold;
color: #FF0000;
}
.my3rdNewStyle {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-weight: bold;
font-size: 12pt;
color: #FF0000;
}
In the above example I have created a series CSS classes that can be applied
to any HTML tag like so:
<p class="myNewStyle">My CSS styled text</p>
or
<h2 class=”my3rdNewStyle”>My CSS styled text</h2>
You will notice that in the above example I applied a CSS style to a <h2>
tag. This tag sets the size of the text that it wraps, to a size that is preset
in the browser (ex: 10 pixels). When you apply a CSS class to it, the CSS code
overrides the default size that you would normally get with an <h2> tag
in favor of the size specified in the CSS class. So now you can see that CSS
can override default HTML tag behavior!
In the above examples, I have CSS code where I define my CSS classes and then
‘apply’ them to various elements in the page. Another way to apply
CSS is to globally redefine a HTML tag to look a certain way:
h1 { font-family: Garamond, "Times New Roman", serif; font-size:
200%; }
What this CSS code does is set the font style and size of all <h1> tags
in one shot. Now you don’t have to apply a CSS class as we did before to
any <h1> tags since they are automatically all affected by the CSS style
rules.
Here is another example of where I give the whole page bigger margins:
body { margin-left: 15%; margin-right: 15%; }
As you can see, you can redefine any tag and change the way it looks! This
can be very powerful:
div {
background: rgb(204,204,255);
padding: 0.5em;
border: 1px solid #000000;
}
Set in the above code, any <div></div> tag will now have a background
color of ‘rgb(204,204,255)’ and have a padding of 0.5em and a thin
1 pixel border that is solid black.
A few things to explain about the above:
Color in CSS can be expressed in a few ways:
1. In Hex -> for example: #000000 – this is black and this: #FF0000
is red.
2. In rgb -> rgb(204,204,255) is a light purple blue color.
3. With named colors like: ‘red’ or ‘blue’
I typically use hex color since I am familiar with them or I just use named
colors. So the last example can be rewritten like so:
div {
background: green;
padding: 0.5em;
border: 1px solid #FF0000;
}
So instead of ‘rgb(204,204,255)’ , I just specified ‘green’.
By using RGB (RGB is the acronym for: ‘Red Green Blue’) and Hex color,
you can really get the exact color you want easily when you know your codes.
Luckily many programs (like Dreamweaver) provide easy to use color pickers for
you so you don’t need to know the values for the code.
In this last example I will show you the ‘super cool’ CSS code that
allows you to create link roll-over affects without images:
:link { color: rgb(0, 0, 153) } /* for unvisited links */
:visited { color: rgb(153, 0, 153) } /* for visited links */
:hover { color: rgb(0, 96, 255) } /* when mouse is over link */
:active { color: rgb(255, 0, 102) } /* when link is clicked */
The above CSS will cause your links to change color when someone hovers their
mouse pointer over it, instant rollovers with no images! One important note
with the above code is that it is important that the style declarations be in
the right order: "link-visited-hover-active", otherwise it may break
it in some browsers.
CSS is very powerful and allows you to do things that you can’t do with
standard HTML. It is supported nicely now in all the modern browsers and is
a must learn tool for web designers. The above examples are just a small sample
of what you can do with CSS, but it should be more than enough for you to start
styling your pages nicely. Like with many technologies CSS has a lot of capability
that most people will not need to use often if at all. Don’t get caught
in the trap of thinking that if there is some functionality/feature available
that you have to use it.
BTW: The killersites forum has a great feature that allows you to do some pretty
powerful searches against what was discussed. For example if you type ‘CSS’
in the search box you will get a list of all the post regarding CSS. This feature
will make the forum archive a great source of information as it builds as people
continue to ask and answer various questions on web design.
A final comment:
A great site to look at is the Zen Garden. This website is: 'A demonstration
of what can be accomplished visually through CSS based design.'
Another greate site on CSS by Eric Meyer.
About the author: Stefan Mischook has been developing websites for 10 years.
Experienced with Java/J2EE, PHP, ASP.NET and many other web related technologies,
he now writes about web design on the popular websites www.killersites.com and
www.how-to-build-websites.com |
