Webpage Design: HTML & style sheets
In HTML it is possible to add colours, fonts and other styles to the web pages that you build, however this is not recommended and HTML should be used for structure only. To add colours, fonts, etc. we will use Cascading Style Sheets, also known as CSS.
Style rules edit
A style sheet is made up of Style Rules. Each Style Rule has three parts, a selector, a property and a value:
selector {property : value}
For multiple properties you separate them using a semicolon;
selector {property1 : value1; property2 : value2}
Selectors edit
selector {property : value}
You need to know three types of selector:
- type, selects all elements of a certain type on the page e.g.
h1 { color : green}selects all the heading 1s and turns them green - class, selects all elements of the class you have specified and applies the style to only those elements
.classname { color : red} - ID, selects the item with the single ID that you have specified
#idname { color : blue }. You can only apply an ID once in an HTML document
| CSS Property | Description | CSS Values | Example for Heading 1 | Output |
|---|---|---|---|---|
| font-style: | Changes the font style of text elements | normal, italic, oblique | h1 { font-style : italic } |
Hello |
| font-weight: | Define how bold text is | bold, normal, 400 | h1 { font-weight : bold } |
Hello |
| background-color: | Define page or item background colour | green, brown, yellow | h1 { background-color : yellow } |
Hello |
| text-align: | horizontal position of text | center, left, right | h1 { text-align : center } |
|
| font-family: | define the font of page text | "Times New Roman", Arial, Helvetica | h1 { font-family : "Times New Roman" } |
Hello |
| font-size: | define the size of page text | 100%, 250%, 50% | h1 { font-size : 250% } |
Hello |
| color: | changes the foreground colour of an element | green, brown, orange | h1 { color : green } |
Hello |
| (EXTENSION) text-decoration: | Allows for underlining, strikethrough etc. | overline, underline, line-through | h1 { text-decoration : underline } |
Hello |
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Exercise: CSS rules Write CSS rules to do the following: Answer:
h3 { color : blue}
Turn all paragraphs red and itallic: Answer:
p { color : red; font-style : italic}
Turn all class=bbold: bold and blue Answer:
.bbold { color : blue; font-weight: bold}
Turn all class=uit: underlined and italic Answer:
.uit { text-decoration : underline; font-style : italic }
Name the three components of a CSS style rule: Answer:
selector {property: value}
Name the three different types of selector and describe each: Answer:
Describe the difference between HTML and CSS: Answer:
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Type edit
h1 { color : green }
Take the HTML behind a simple website:
<html>
<head>
<title>My Website</title>
</head>
<body>
<h1>Welcome</h1>
<p>This is my amazing website, look how great it is! </p>
<p>I doubt you could find a better one anywhere on the web.</p>
<p>Seriously!</p>
</body>
</html>
As we probably know, this would build the following page:
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Address |  |
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Welcome
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
You might think my claims are a little over the top, but we could try to make the site better by adding some colour to the title using the following CSS rules:
h1 { color : green }
p { color : red; font-style : italic }
We can't just place this directly into the page, we have to create a new section inside the <head> </head> tags, this is called embedding CSS, we'll look at another method, External Style Sheets later:
<html>
<head>
<title>My Website</title>
<style TYPE="text/css">
<!--
h1 { color : green }
p { color : red; font-style : italic }
-->
</style>
</head>
<body>
<h1>Welcome</h1>
<p> This is my amazing website, look how great it is!</p>
<p>I doubt you could find a better one anywhere on the web.</p>
<p>Seriously!</p>
</body>
</html>
What this will do is change the heading to green, and change each paragraph to red and italic:
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Address | |
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Welcome
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
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Exercise: CSS Type Selectors For the HTML code below, show what the output would be for each set of CSS rules: <html>
<head>
<title>My Website2</title>
</head>
<body>
<h1>Contact Details</h1>
<p>Please use the details below to get in contact</p>
<h2>Telephone</h2>
<p>Home: 0101010101010<br />
Mobile: 1010101010101<br />
</p>
<h2>Email</h2>
<p>1010101@10100101.com</p>
</body>
</html>
What would these two rules produce? h2 { color : red }
h1 { color : blue; text-decoration : underline }
Answer:
My Website2
Contact Details Email 1010101@10100101.com
What would these two rules produce? p { font-weight : bold }
h1 { font-style : italic }
Answer:
My Website2
Contact Details Email 1010101@10100101.com
Write rules to produce the following output:
My Website2
Contact Details Email 1010101@10100101.com Answer:
h1 { color : red; }
h2 { text-decoration : underline}
Write rules to produce the following output:
My Website2
Contact Details Email 1010101@10100101.com Answer:
h1 { background-color : yellow; }
h2 { text-decoration : underline }
p { background-color : red}
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Class edit
.classname {property1 : value1; property2 : value2}
Take another look at the HTML behind a simple website:
<html>
<head>
<title>My Website</title>
</head>
<body>
<h1 class="textb">Welcome</h1>
<p class="textb">This is my amazing website, look how great it is!
<p class="texts">I doubt you could find a better one anywhere on the web.
<p class="textb">Seriously!
</body>
</html>
As you can see there are classes attached to some of the HTML tags, namely the 'textb' and 'texts' classes. On their own they don't do anything, we need to write some CSS style rules to make them come to life, remember that a class selector starts with a (.).
.textb { color : red; text-decoration : underline }
.texts { font-style : italic }
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Address | |
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Welcome
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
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Exercise: CSS Class Selectors For the HTML code below, show what the output would be for each set of the CSS rules: <html>
<head>
<title>My Website3</title>
</head>
<body>
<h1 class="txtt">Contact Details</h1>
<p>Please use the details below to get in contact</p>
<h2 class="txtg">Telephone</h2>
<p class="txtt">Home: 0101010101010<br />
Mobile: 1010101010101<br />
</p>
<h2>Email</h2>
<p class="txtg">1010101@10100101.com</p>
</body>
</html>
What would these two rules produce? .txtg { color : blue }
Answer: note that class="txtt" does nothing as the CSS doesn't define it.
My Website3
Contact Details Email 1010101@10100101.com
.txtg { color : red }
.txtt { text-decoration : underline; color : green }
Answer:
My Website3
Contact Details Email 1010101@10100101.com
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ID edit
#idname { color : blue }
Take yet another look at the HTML behind a simple website:
<html>
<head>
<title>A Website</title>
</head>
<body>
<h1 class="textb">Welcome</h1>
<p id="para1">This is my amazing website, look how great it is!
<p id="para2">I doubt you could find a better one anywhere on the web.
<p id="para3">Seriously!
</body>
</html>
As you can see, I have assigned an id to each of the paragraphs, this means that I can now style them separately from each other. Remember that an ID selector starts with a #.
#para1 { color : red }
#para2 { color : white }
#para3 { color : blue }
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Address | |
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Welcome
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
Each id rule applies to a different paragraph, unfortunately I set #para2 to white, so you can't see it!
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Exercise: CSS ID Selectors For the HTML code below, show what the output would be for each set of the CSS rules: <html>
<head>
<title>My Website3</title>
</head>
<body>
<h1 id="main">Contact Details</h1>
<p>Please use the details below to get in contact</p>
<h2>Telephone</h2>
<p>Home: 0101010101010<br />
Mobile: 1010101010101<br />
</p>
<h2>Email</h2>
<p id="txthighlight">1010101@10100101.com</p>
</body>
</html>
What would these two rules produce? #main{ color : green }
#txthighlight{ background-color : yellow }
Answer:
My Website3
Contact Details Email 1010101@10100101.com
Write the CSS to produce the following:
My Website3
Contact Details Email Answer:
#main{ font-style : italic }
#txthighlight{ text-align : center }
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Style sheets (Cascading Style Sheets or CSS) edit
You should be pretty comfortable with the use of CSS rules, we are now going to look how these rules are linked with the HTML. As we know the style (CSS) of a web page’s contents should to be separated from its structure (HTML), and when these two things come together, it creates the page that you see in your web browser. There are two methods of linking style to structure that you need to know:
- Embedded style, blocks of CSS information inside the HTML document
- External style sheets, i.e., a separate CSS file referenced from the HTML document
Embedded style edit
Blocks of CSS information inside the HTML document. You can see that inside the head tag we have a block of CSS that applies to the HTML below it:
<html>
<head>
<title>My Website</title>
<style type="text/css">
<!--
h1 { font-weight : 900 }
.highlight {color : yellow }
-->
</style>
</head>
<body>
<h1>Welcome</h1>
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
</body>
</html>
External style sheets edit
External style sheets use a separate file to store the style information (a .css file) and link the file from inside the HTML document.
<html>
<head>
<title>My Website</title>
<link href="style.css" rel="stylesheet" type="text/css">
</head>
<body>
<h1>Welcome</h1>
This is my amazing website, look how great it is!
I doubt you could find a better one anywhere on the web.
Seriously!
</body>
</html>
h1 { font-weight : 900 }
.highlight {color : yellow }
As you can see above the HTML file links to the CSS file through the line:
<link href="style.css" rel="stylesheet" type="text/css">
. You could get an HTML page to link to multiple CSS files and link a CSS file from multiple HTML files.
External style sheets are a better way of linking CSS to HTML than embedding CSS in HTML as you can:
Link one CSS file to many HTML files to reuse the same style without needing to retype it When changing the style of a website you only need to change the style information in one location and it'll filter through to all pages
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Exercise: Types of style sheet Name the two different style sheets: Answer:
Why might you prefer to use external style sheets on a large web site? Answer: You can link the same style sheet from multiple pages and changes to the site style would only require changes to that one style sheet |
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Extension:CSS3
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