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HTML Beginner Tutorial - Lists

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:29 pm - 452 views

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There are three types of list; unordered lists, ordered lists and definition lists. We will look at the first two here, and definition lists in the HTML Intermediate Tutorial.

 

Unordered lists and ordered lists work the same way, except that the former is used for non-sequential lists with list items usually preceded by bullets and the latter is for sequential lists, which are normally represented by incremental numbers.

The ul tag is used to define unordered lists and the ol tag is used to define ordered lists. Inside the lists, the li tag is used to define each list item.

Change your code to the following:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>

<html>

<head>
	<title>My first web page</title>
</head>

<body>
	<h1>My first web page</h1>

	<h2>What this is</h2>
	<p>A simple page put together using HTML</p>

	<h2>Why this is</h2>
	<ul>
		<li>To learn HTML</li>
		<li>To show off</li>
		<li>Because I’ve fallen in love with my computer and want to give her some HTML loving.</li>
	</ul>

</body>

</html>

If you look at this in your browser, you will see a bulleted list. Simply change the ul tags to ol and you will see that the list will become numbered.

Lists can also be included in lists to form a structured hierarchy of items.

Replace the above list code with the following:


<ul>
	<li>To learn HTML</li>
	<li>
		To show off
		<ol>
			<li>To my boss</li>
			<li>To my friends</li>
			<li>To my cat</li>
			<li>To the little talking duck in my brain</li>
		</ol>
	</li>
	<li>Because I’ve fallen in love with my computer and want to give her some HTML loving.</li>
</ul>

Et voil?. A list within a list. And you could put another list within that. And another within that. And so on and so forth.

HTML Beginner Tutorial - Links

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:26 pm - 703 views

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So far you’ve been making a stand-alone web page, which is all very well and nice, but what makes the internet so special is that it all links together.

The ‘H’ and ‘T’ in ‘HTML‘ stand for ‘hypertext‘, which basically means a system of linked text.

 

An anchor tag (a) is used to define a link, but you also need to add something to the anchor tag - the destination of the link.

Add this to your document:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>

<html>

<head>
	<title>My first web page</title>
</head>

<body>

	<h1>My first web page</h1>

	<h2>What this is</h2>
	<p>A simple page put together using HTML</p>

	<h2>Why this is</h2>
	<p>To learn HTML</p>

	<h2>Where to find the tutorial</h2>
	<p><a href=“http://www.programimi.com”>ProgramimiCOM</a></p>

</body>

</html>

The destination of the link is defined in the href attribute of the tag. The link can be absolute, such as “http://www.programimi.com”, or it can be relative to the current page.

So if, for example, you had another file called “flyingmoss.html” then the line of code would simply be <a href="flyingmoss.html">The miracle of moss in flight</a> or something like this.

A link does not have to link to another HTML file, it can link to any file anywhere on the web.

A link can also send a user to another part of the same page they are on. You can add an id attribute to just about any tag, for example <h2 id="moss">Moss</h2>, and then link to it by using something like this: <a href="#moss">Go to moss</a>. Selecting this link will scroll the page straight to the element with that id.

The a tag allows you to open the link in a newly spawned window, rather than replacing the web page the user is on, which at first thought may sound like a good idea as it doesn’t take the user away from your site.

There are a number of reasons why you shouldn’t do this however.

From a usability point of view, this method breaks navigation. The most commonly used navigation tool on a browser is the “back” button. Opening a new window disables this function.

On a wider, more general usability point, users do not want new windows to be popping up all over the place. If they want to open a link in a new window then they can choose to do so themselves.

HTML Beginner Tutorial - Images

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:23 pm - 393 views

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Things might seem a little bland and boring with all of this text formatting. Of course, the web is not just about text, it is multi-media and the most common form of media is the image.

 

The img tag is used to put an image in an HTML document and it looks like this:


<img src=”http://www.programimi.com/wp-content/themes/limau-orange-01/images/logo.gif” width=”301? height=”56? alt=”ProgramimiCOM” />

The src attribute tells the browser where to find the image. Like the a tag, this can be absolute, as the above example demonstrates, but is usually relative. For example, if you create your own image and save it as “alienpie.jpg” in a directory called “images” then the code would be <img src="images/alienpie.jpg"...

The width and height attributes are necessary because if they are excluded, the browser will tend to calculate the size as the image loads, instead of when the page loads, which means that the layout of the document may jump around while the page is loading.

The alt attribute is the alternative description. This is used for people who cannot or choose not to view images. This is a requirement in the latest versions of HTML.

Note that, like the br tag, because the img tag does not have a closing tag, it closes itself, ending with “/>”

The construction of images for the web is a little outside of the remit of this website, but it is worth noting a few things…

The most commonly used file formats used for images are GIFs and JPEGs. They are both compressed formats, and have very different uses.

GIFs can have no more than 256 colours, but they maintain the colours of the original image. The lower the number of colours you have in the image, the lower the file size will be.

GIFS SHOULD BE USED FOR IMAGES WITH SOLID COLOURS.

JPEGs on the other hand use a mathematical algorithm to compress the image and will distort the original slightly. The lower the compression, the higher the file size, but the clearer the image.

JPEGS SHOULD BE USED FOR IMAGES SUCH AS PHOTOGRAPHS.

Images are perhaps the largest files a new web designer will be handling. It is a common mistake to be oblivious to the file size of images, which can be extremely large. Web pages should download as quickly as possible, and if you keep in mind that most people still use modems that download at less than 7Kb a second (realistically it is less than 5Kb), you can see how a large file will greatly slow down the download time of a full page.

You need to strike a balance between image quality and image size. Most modern image manipulation programs allow you to compress images and the best way to figure out what is best suited for yourself is trial and error.

HTML Beginner Tutorial - Tables

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:19 pm - 468 views

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Across the worldwide web, HTML tables are used and abused to layout pages. We will come across how to layout a page without tables, in the CSS Advanced Tutorial. The correct use for tables is to do exactly what you would expect a table to do - to structure tabular data.

 

There are a number of tags used in tables, and to fully get to grips with how they work is probably the most difficult area of this HTML Beginners Tutorial.

Copy the following code into the body of your document and then we will go through what each tag is doing:


<table>
	<tr>
		<td>Row 1, cell 1</td>
		<td>Row 1, cell 2</td>
		<td>Row 1, cell 3</td>
	</tr>
	<tr>
		<td>Row 2, cell 1</td>
		<td>Row 2, cell 2</td>
		<td>Row 2, cell 3</td>
	</tr>
	<tr>
		<td>Row 3, cell 1</td>
		<td>Row 3, cell 2</td>
		<td>Row 3, cell 3</td>
	</tr>
	<tr>
		<td>Row 4, cell 1</td>
		<td>Row 4, cell 2</td>
		<td>Row 4, cell 3</td>
	</tr>
</table>

The table element defines the table.

The tr element defines a table row.

The td element defines a data cell. These must be enclosed in tr tags, as shown above.

If you imagine a 3×4 table, which is 12 cells, there should be four tr elements to define the rows and three td elements within each of the rows, making a total of 12 td elements.

HTML Beginner Tutorial - Forms

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:17 pm - 676 views

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Forms can be used to send data across the web and are often used as contact forms to convert information inputted by a user into an email.

 

On their own, forms are useless. They need to be hooked up to a program that will process the data inputted by the user. These take all manner of guises and are outside of the remit of this website. If you use an internet service provider to host your HTML, they will be able to help you with this and will probably have clear and simple instructions on how, for example, to make a form-to-email form work.

The basic tags used in the actual HTML of forms are form, input, textarea, select and option.

form defines the form and within this tag, there is one required action attribute which tells the form where its contents will be sent to when it is submitted.

The optional method attribute tells the form how the data in it is going to be sent and it can have the value get (which is default) or post. This is commonly used, and often set to post which hides the information (get latches the information onto the URL).

So a form element will look something like this:


<form action=“processingscript.php” method=“post”>

</form>

The input tag is the daddy of the form world. It can take ten forms, outlined below:

  • <input type=”text” /> is a standard textbox. This can also have a value attribute, which sets the initial text in the textbox.
  • <input type=”password” /> is similar to the textbox, but the characters typed in by the user will be hidden.
  • <input type=”checkbox” /> is a checkbox, which can be toggled on and off by the user. This can also have a checked attribute, which would be used in the format <input type="checkbox" checked="checked" />, and makes the initial state of the check box to be switched on, as it were.
  • <input type=”radio” /> is similar to a checkbox, but the user can only select one radio button in a group. This can also have a checked attribute, used in the same way as the checkbox.
  • <input type=”file” /> is an area that shows the files on your computer, like you see when you open or save a document in most programs, and is used to enable users to upload files.
  • <input type=”submit” /> is a button that when selected will submit the form. You can control the text that appears on the submit button (as you can with button and reset types - see below) with the value attribute, for example <input type="submit" value=”Ooo. Look. Text on a button. Wow” />.
  • <input type=”image” /> is an image that will submit the coordinates of where the user clicked on it. This also requires a src attribute, like the img tag.
  • <input type=”button” /> is a button that will not do anything without extra code added.
  • <input type=”reset” /> is a button that when selected will reset the form fields to their default values.
  • <input type=”hidden” /> is a field that will not be displayed and is used to pass information such as the page name that the user is on or the email address that the form should be posted to.

Note that the input tag closes itself with a “/>” at the end.

A textarea is, basically, a large textbox. It requires a rows and cols attribute and is used like this:

<textarea rows="5" cols="20">A big load of text here</textarea>

The select tag works with the option tag to make drop-down select boxes.

They work like this:


<select>
	<option value=“first option”>Option 1</option>
	<option value=“second option”>Option 2</option>
	<option value=“third option”>Option 3</option>
</select>

When the form is submitted, the value of the selected option will be sent.

Similar to the checked attribute of checkboxes and radio buttons, an option tag can also have a selected attribute, which would be used in the format <option value="mouse" selected="selected">Rodent</option>.

All of the tags mentioned above will look very nice presented on the page, but if you hook up your form to a form-handling program, they will all be ignored. This is because the form fields need names. So to all of the fields, the attribute name needs to be added, for example <input type="text" name="talkingsponge" />

A form might look like the one below. (Note: this form will not work unless there is a “contactus.php” file, which is stated in the action attribute of the form tag, to handle the submitted date)


<form action=“contactus.php” method=“post”>

	<p>Name:</p>
	<p><input type=“text” name=“name” value=“Your name” /></p>

	<p>Comments: </p>
	<p><textarea name=“comments” rows=“5″ cols=“20″>Your comments</textarea></p>

	<p>Are you:</p>
	<p><input type=“radio” name=“areyou” value=“male” /> Male</p>
	<p><input type=“radio” name=“areyou” value=“female” /> Female</p>
	<p><input type=“radio” name=“areyou” value=“hermaphrodite” /> An hermaphrodite</p>
	<p><input type=“radio” name=“areyou” value=“asexual” checked=“checked” /> Asexual</p>

	<p><input type=“submit” /></p>

	<p><input type=“reset” /></p>

</form>

There is a whole other level of complexity you can delve into in the HTML Advanced Tutorial if you are so inclined.

HTML Beginner Tutorial - Putting It All Together

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 8:13 pm - 312 views

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If you have gone through all of the pages in this HTML Beginner Tutorial then you should be a competent HTMLer.

In fact, due to the fact that most people who use HTML use it rather badly, you should be better than most.

 

The following code incorporates all of the methods that have been explained in the previous pages:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>

<html>

<head>

	<title>My first web page</title>

	<!– By the way, this is a comment –>

</head>

<body>

<h1>My first web page</h1>

<h2>What this is</h2>
<p>A simple page put together using HTML. <strong>A simple page put together using HTML.</strong> A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML.</p>

<h2>Why this is</h2>
<ul>
	<li>To learn HTML</li>
	<li>
		To show off
		<ol>
			<li>To my boss</li>
			<li>To my friends</li>
			<li>To my cat</li>
			<li>To the little talking duck in my brain</li>
		</ol>
	</li>
	<li>Because I‘ve fallen in love with my computer and want to give her some HTML loving.</li>
</ul>

<h2>Where to find the tutorial</h2>
<p><a href=”http://www.programimi.com”><img src=”http://www.programimi.com/wp-content/themes/limau-orange-01/images/logo.gif” width=”301″ height=”56″ alt=”ProgramimiCOM” /></a></p>

<h3>Some random table</h3>
<table border=”1″>
	<tr>
		<td>Row 1, cell 1</td>
		<td>Row 1, cell 2</td>
		<td>Row 1, cell 3</td>
	</tr>
	<tr>
		<td>Row 2, cell 1</td>
		<td>Row 2, cell 2</td>
		<td>Row 2, cell 3</td>
	</tr>
	<tr>
		<td>Row 3, cell 1</td>
		<td>Row 3, cell 2</td>
		<td>Row 3, cell 3</td>
	</tr>
	<tr>
		<td>Row 4, cell 1</td>
		<td>Row 4, cell 2</td>
		<td>Row 4, cell 3</td>
	</tr>
</table>

<h3>Some random form</h3>
<p><strong>Note:</strong> It looks the part, but won’t do a damned thing</p>

<form action=“somescript.php” method=“post”>

<p>Name:</p>
<p><input type=“text” name=“name” value=“Your name” /></p>

<p>Comments: </p>
<p><textarea rows=“10″ cols=“20″ name=“comments”>Your comments</textarea></p>

<p>Are you:</p>
<p><input type=“radio” name=“areyou” value=“male” /> Male</p>
<p><input type=“radio” name=“areyou” value=“female” /> Female</p>
<p><input type=“radio” name=“areyou” value=“hermaphrodite” /> An hermaphrodite</p>
<p><input type=“radio” name=“areyou” value=“asexual” checked=“checked” /> Asexual</p>

<p><input type=“submit” /></p>

<p><input type=“reset” /></p>

</form>

</body>

</html>

There you have it. Save the file and play around with it - this is the best way to understand how everything works. Go on. Tinker.

When you’re happy, you can move on to the CSS Beginner Tutorial.

Member Managment System Using PHP, AJAX - Part 3

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 7:51 pm - 965 views

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In parts one and two of this tutorial we covered the user side of things, now we have to handle our administration area. This is going to be pretty simple, but the cool thing is that it will integrate totally with all our existing code.

In order to protect the PM page from guests, we set our MIN_AUTH_LEVEL constant to 1, so all we need to do in order to only let administrators in is to make that value 2. Sweet.

All the admin panel will do is let you edit users data (not password, you sneaky little. . .) and gives a simple splash page with some basic stats.

File: admin.php

 

<?php
session_start();
//Only administrators can get in here
define(‘MIN_AUTH_LEVEL’, ‘2′);
include(‘./config.php’);
//Only one option, eh.
$menubar = ‘<table><tr><td><a href=”?do=users”>Manage Users</a></td></tr></table>’;
$footer = “<p><a href=’”. SITE_URL .“‘>Home</a> - <a href=’”. SITE_URL .“login.php?do=logout’>Logout</a></p>”;
if($_GET[‘do’] == ”)
{
//Basic information, pretty much useless in our case, but may not be for others
$title = ‘Admin Home’;
$con = “<h2>Admin Home</h2>
Quick Stats:
<ul>
<li>Members: “. count_tbl(‘users’) .“</li>
<li>PM’s: “. count_tbl(‘messages’) .“</li>
</ul>”;
}

The above is just setting the auth level, than doing our simple, and rather pointless, splash page. Next up is the cool part, the user editing. No, there’s no reloading the page, you just click save or delete and it’s done, all with some pretty effects. We’re going to use our get_all_users() function to return a neat array of every user, then all we do is foreach() through each one.

File: admin.php (continued)

 

else if($_GET[‘do’] == ‘users’)
{
//Get an array of every user we have
$users = list_all_users();
$title = “Manage Users”;
$con = “<h2>Manage Users</h2>
<p>Click the save icon to update the user’s details, and the x to delete the user (not undoable!)</p>
<form>
<table border=’1′>
<tr><th>Username</th><th>Name</th><th>E-Mail</th><th>Auth Level</th><th>Options</th></tr>”;
//A mess of code, I know. It lists the details for every user, except password, and assigns each TD a unique ID so that the JS can get the value when saving. The icons let you save your work or delete the user.
foreach($users as $v)
{
$con .= “<tr id=’user_{$v[’id’]}’><td><input type=’text’ id=’username_{$v[’id’]}’ value=’{$v[’username’]}’ /></td><td><input type=’text’ id=’name_{$v[’id’]}’ value=’{$v[’name’]}’ /></td><td><input type=’text’ id=’email_{$v[’id’]}’ value=’{$v[’email’]}’ /></td><td><input type=’text’ id=’auth_{$v[’id’]}’ value=’{$v[’admin’]}’ /></td><td align=’center’><a href=’#’ onclick=\”edit_user(’{$v[’id’]}’);\”><img src=’./images/save.png’ alt=’save’ style=’border:none;’ /></a> - <a href=’#’ onclick=\”delete_user(’{$v[’id’]}’, ‘{$v[’username’]}’);\”><img src=’./images/delete.png’ style=’border:none;’ alt=’delete’ /></a></td></tr>”;
}
$con .= “</table></form>”;
}
?>

There’s not much going on there other than the mass of ugly looking code. The $v variable is the array of the current user’s details, which is assigned by the foreach loop. Now comes the hard part, well kind of, the JavaScript. After this we’ll be done! :)

File: admin.php (continued)

 

<html>
<head>
<title><?php echo $title; ?></title>
<script src=‘../../scriptaculous/prototype.js’></script>
<script src=‘../../scriptaculous/scriptaculous.js’></script>
<script type=‘text/javascript’>
//Get every new value, taken from our unique IDs assigned earlier.
function edit_user(uid)
{
var opt = {
method:‘post’,
postBody:‘m=edituser&id=’ + uid + ‘&username=’ + $F(‘username_’ + uid) + ‘&email=’ + $F(‘email_’ + uid) + ‘&name=’ + $F(‘name_’ + uid) + ‘&auth=’ + $F(‘auth_’ + uid) +‘&password=<?php echo $user[’password‘]; ?>’,
onSuccess: function(t) { handle_edit(t, uid); }
}
new Ajax.Request(‘./ajax.php’, opt);
}

function handle_edit(t, uid)
{
if(t.responseText == “1″)
{
//Give a pretty notice to say that it was saved
new Effect.Highlight(‘user_’ + uid);
}
else
{
alert(“The user’s data was not updated, please try again.”);
}
}

function delete_user(uid, username)
{
//Confirm the delete
if(confirm(“Are you sure you want to delete “ + username + “?”))
{
var opt = {
method:‘post’,
postBody:‘m=deluser&id=’ + uid + ‘&password=<?php echo $user[’password‘]; ?>’,
onSuccess: function(t) { handle_delete(t, uid); }
}
new Ajax.Request(‘./ajax.php’, opt);
}
}

function handle_delete(t, uid)
{
if(t.responseText == “1″)
{
//Remove the user from the table very nicely :)
new Effect.Fade(‘user_’ + uid);
}
else
{
//Agh!
alert(“The user was not deleted, please try again.”);
}
}
</script>
</head>
<body>
<?php echo $menubar, $con, $footer; ?>
</body>
</html>

You should be familar with making AJAX requests now, you may notice our use of Effect.FadeOut and Effect.Highlight, these are just built in script.aculo.us effects that make UI very pretty. This is it for the tutorial, it’s definitly been a long one. I’ll try to get a working version up soon with public admin access, but I’ll have to modify some code so you guys don’t go to overboard.

A full set of files used in this tutorial can be downloaded here

CSS Beginner Tutorial - Applying CSS

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 7:49 pm - 761 views

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There are three ways to apply CSS to HTML.

 

 

In-line

In-line styles are plonked straight into the HTML tags using the style attribute.

They look something like this:


<p style=“color: red”>text</p>

This will make that specific paragraph red.

But, if you remember, the best-practice approach is that the HTML should be a stand-alone, presentation free document, and so in-line styles should be avoided wherever possible.

Internal

Embedded, or internal styles are used for the whole page. Inside the head tags, the style tags surround all of the styles for the page.

This would look something like this:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>
<html>
<head>
<title>CSS Example</title>
<style type=“text/css”>
	p {
		color: red;
	}

	a {
		color: blue;
	}
</style>
…

This will make all of the paragraphs in the page red and all of the links blue.

Similarly to the in-line styles, you should keep the HTML and the CSS files separate, and so we are left with our saviour…

External

External styles are used for the whole, multiple-page website. There is a separate CSS file, which will simply look something like:


p {
	color: red;
}

a {
	color: blue;
}

If this file is saved as “web.css” then it can be linked to in the HTML like this:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>
<html>
<head>
	<title>CSS Example</title>
	<link rel=“stylesheet” type=“text/css” href=“web.css” />
…

In the CSS Advanced Tutorial, we will see that there are other ways of linking external style sheets, but this will suffice for now.

To get the most from this guide, it would be a good idea to try out the code as we go along, so start a fresh new file with your text-editor and save the blank document as “web.css” in the same directory as your HTML file.

Now change your HTML file so that it starts something like this:


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>

<html>

<head>
	<title>My first web page</title>
	<link rel=“stylesheet” type=“text/css” href=“web.css” />
</head>
…

Save the HTML file. This now links to the CSS file, which is empty at the moment, so won’t change a thing. As you work your way through the CSS Beginner Tutorial, you will be able to add to and change the CSS file and see the results by simply refreshing the browser window that has the HTML file in it, as we did before.

CSS Beginner Tutorial - CSS Selectors, Properties, and Values

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 7:47 pm - 348 views

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Whereas HTML has tags, CSS has ‘selectors‘. Selectors are the names given to styles in internal and external style sheets. In this CSS Beginner Tutorial we will be concentrating on HTML selectors, which are simply the names of HTML tags and are used to change the style of a specific tag.

 

For each selector there are ‘properties‘ inside curly brackets, which simply take the form of words such as color, font-weight or background-color.

A value is given to the property following a colon (NOT an ‘equals’ sign) and semi-colons separate the properties.


body {
	font-size: 0.8em;
	color: navy;
}

This will apply the given values to the font-size and color properties to the body selector.

So basically, when this is applied to an HTML document, text between the body tags (which is the content of the whole window) will be 0.8 ems in size and navy in colour.

Lengths and Percentages

There are many property-specific units for values used in CSS, but there are some general units that are used in a number of properties and it is worth familiarising yourself with these before continuing.

em (such as font-size: 2em) is the unit for the calculated size of a font. So “2em”, for example, is two times the current font size.

px (such as font-size: 12px) is the unit for pixels.

pt (such as font-size: 12pt) is the unit for points.

% (such as font-size: 80%) is the unit for… wait for it… percentages.

Other units include pc (picas), cm (centimetres), mm (millimetres) and in (inches).

When a value is zero, you do not need to state a unit. For example, if you wanted to specify no border, it would be border: 0.

A web page is not a static, absolute medium. It is meant to be flexible and the user should be allowed to view the web page how the hell they like, which includes the font size and the size of the screen.

Because of this, it is generally accepted that ‘em’ or ‘%’ are the best units to use for font-sizes (and possibly even heights and widths, which we shall come across in the CSS Advanced Tutorial), rather than ‘px’, which leads to non-resizable text in most browsers, and should be used sparingly, for border sizes for example.

CSS Beginner Tutorial - Colours

22 Jul

Posted by ProCOM bloggeraz on July 22, 2007 – 7:45 pm - 344 views

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CSS brings 16,777,216 colours to your disposal. They can take the form of a name, an rgb (red/green/blue) value or a hex code.

red
Is the same as
rgb(255,0,0)
Which is the same as
rgb(100%,0%,0%)
Which is the same as
#ff0000
Which is the same as
#f00

There are 17 valid predefined colour names. They are aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, orange, purple, red, silver, teal, white, and yellow.

transparent is also a valid value.

The three values in the rbg value are from 0 to 255, 0 being the lowest level (for example no red), 255 being the highest level (for example full red). These values can also be a percentage.

Hexadecimal (previously and more accurately known as ‘sexadecimal‘) is a base-16 number system. We are generally used to the decimal number system (base-10, from 0 to 9), but hexadecimal has 16 digits, from 0 to f.

The hex number is prefixed with a hash character (#) and can be three or six digits in length. Basically, the three-digit version is a compressed version of the six-digit (#f00 becomes #ff0000, #c96 becomes #cc9966 etc.). The three-digit version is easier to decipher (the first digit, like the first value in rgb, is red, the second green and the third blue) but the six-digit version gives you more control over the exact colour.

‘color’ and ‘background-color’

Colours can be applied by using color and background-color (note that this must be the American English ‘color’ and not ‘colour’).

A blue background and yellow text could look like this:


h1 {
	color: yellow;
	background-color: blue;
}

These colours might be a little too harsh, so you could change the code of your CSS file for slightly different shades:


body {
	font-size: 0.8em;
	color: navy;
}

h1 {
	color: #ffc;
	background-color: #009;
}

Save the CSS file and refresh your browser. You will see the colours of the first heading (the h1 element) have changed to yellow and blue.

You can apply the color and background-color properties to most HTML elements, including body, which will change the colours of the page and everything in it.

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