Ten more CSS tricks you may not know
1. Block vs. inline level elements
Every HTML element is either a block or inline element. The characteristics
of block elements include:
- Always begin on a new line
- Height, line-height and top and bottom margins can be manipulated
- Width defaults to 100% of their containing element, unless a width is specified
Example of block elements include <div>, <p>, <h1>, <form>,
<ul> and <li>. Inline elements on the other hand have the
opposite characteristics:
- Begin on the same line
- Height, line-height and top and bottom margins can't be changed
- Width is as long as the text/image and can't be manipulated
Example of inline elements include <span>, <a>, <label>,
<input>, <img>, <strong> and <em>.
To change an element's status you can use display: inline or display: block.
But what's the point of changing an element from being block to inline, or vice-versa?
Well, at first it may seem like you might hardly ever use this, but in actual
fact this is a very powerful technique, which you can use any time you want
to:
- Have an inline element start on a new line
- Have a block element start on the same line
- Control the width of an inline element (particularly useful for navigation
links)
- Manipulate the height of an inline element
- Set a background colour as wide as the text for block elements, without
having to specify a width
2. Another box model hack alternative
The box
model hack is used to fix a rendering problem in pre-IE 6 browsers on PC,
where by the border and padding are included in the width of an element, as
opposed to added on. A number of CSS-based solutions have been put forward to
remedy this, so here's another one which we really like:
padding: 2em;
border: 1em solid green;
width: 20em;
width/**/:/**/ 14em;
The first width command is read by all browsers; the
second by all browsers except IE5.x on PC. Because the second command comes second
it takes precedence over the first. So, how does this work?
By placing empty comment tags (/**/) before the colons, IE5.0 will ignore the
command. Likewise, by placing these empty comment tags after the colon, IE5.5
will ignore the command. By using these two rules in conjunction with each other,
we can hide the command from all of IE5.x.
3. Minimum width for a page
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 <div>
under the <body> tag, as we can't assign a minimum width to the <body>:
<body>
<div class="container">
Next we create our CSS commands, so as to create a minimum width of 600px:
#container
{
min-width: 600px;
width:expression(document.body.clientWidth < 600? "600px": "auto"
);
}
The first command is the regular minimum width command; the second is a short
JavaScript command that only IE understands. Do note though, this command will
cause your CSS document to invalidate so you may prefer to insert it into the
head of each HTML document to get round this.
You might also want to combine this minimum width with a maximum width:
#container
{
min-width: 600px;
max-width: 1200px;
width:expression(document.body.clientWidth < 600? "600px" : document.body.clientWidth
> 1200? "1200px" : "auto");
}
4. IE and width & height issues
IE has a rather strange way of doing things. It doesn't understand the min-width
and min-height commands, but instead interprets width and height as min-width
and min-height - go figure!
This can cause problems, because we may need boxes to be resizable should more
text need to go in them or should the user resize text. If we only use the width
and height commands on a box then non-IE browsers won't allow the box to resize.
If we only use the min-width and min-height commands though then we can't control
the width or height in IE!
This can be especially problematic when using background images. If you're
using a background image that's 80px wide and 35px high, then you'll want to
make sure that the default size for a box using this image is exactly 80 x 35px.
However, if users resize the text then the box size will need to expand gracefully.
To resolve this problem, you can use the following code for a box with class="box":
.box
{
width: 80px;
height: 35px;
}
html>body .box
{
width: auto;
height: auto;
min-width: 80px;
min-height: 35px;
}
All browsers will read through the first CSS rule but IE will ignore the second
rule because it makes use of the child selector command. Non-IE browsers will
read through the second one and will override the values from the first rule
because these commands come second, and commands that come second always override
those that come first.
5. Text-transform command
One of the lesser known, but really useful CSS commands is the text-transform
command. Three of the more common values for this rule are: text-transform:
uppercase, text-transform: lowercase and text-transform: capitalize. The first
rule turns all characters into capital letters, the second turns them all into
small letters, and the third makes the first letter of each word capitals.
This command is incredibly useful to help ensure consistency in style across
an entire website, particularly if there a number of content editors. Say for
example your style guide dictates that words in headings must always begin with
capital letters. To ensure that this is always the case, use text-transform:
capitalize. Even if site editors forget about the capitalisation, their mistake
won't show up on the website.
It's also preferable to use text-transform: uppercase to capitalise words,
as screen readers may pronounce shorter words in capital letters as acronyms.
A great example of this is ‘CONTACT US’, which is pronounced as
‘contact U S’ by some screen readers.
6. Disappearing text or images in IE?
IE has a very strange bug where text or background images sometimes disappears
from sight. These items are still actually there, and if you highlight everything
on screen or hit refresh they'll often re-appear. Kind of strange, huh?
This problem mostly occurs on background images and on text next to a floated
element. To remedy the problem, simply insert position: relative into the CSS
command for the disappearing element, and for some bizarre reason that'll usually
fix the problem. If this doesn't work (it sometimes doesn't), assign a width
to the offending element in the CSS and that should fix the problem.
7. Invisible text
Sometime you may actually want to make text invisible. Invisible text can be
especially useful for screen reader users, perhaps to assign a label to a form
item or insert a heading ahead of a section. Don't want to change the visual
appearance by inserting these? Make them invisible and no one using a visual
browser knows that they're there.
You may also want to make text invisible if using a print or handheld CSS file,
as some information may not need to be displayed on either of these mediums
(see below for more on this).
To make text invisible you can use display: none - easy! This works fine for
hiding text from handhelds (if CSS is supported) and printed web pages, but
isn't so great for many screen readers. Screen readers are now becoming too
clever for their own good, and some will actually ignore the any text that has
the rule display: none assigned to it.
For screen readers users therefore, a new approach is needed: position: absolute;
left: -9000px. This basically takes the text and positions it 9000px to the
left of the left edge of the screen, essentially making it invisible.
8. CSS document for handhelds
A separate CSS document can be created for PDAs and mobile phones, and only
activated when one of these devices is being used to access your site. More
and more websites are creating separate CSS documents for printing, so web pages
automatically become print-friendly when users choose to print them. You can
also do the same for handheld devices.
The following command is used to call up the CSS document for handhelds:
<link type="text/css" rel="stylesheet" href="handheldstyle.css"
media="handheld" />
CSS commands in the handheld CSS file override any equivalent commands in the
main CSS document. So, what commands should you place in this file?
Ideally, you want handheld web users to avoid having to scroll across. To test
this, open up your website in a regular browser window and resize it to 150px
in width. Then, open up your main CSS file and insert some new commands at the
very bottom of the document. The commands you place here should adjust the layout
of the website so that it doesn't require horizontal scrolling at a 150px width.
Then, open up a new document, cut and paste these new commands over, and save
it as handheldstyle.css (or whatever name you want to give it).
What your website offers to handheld web users should be quite different to
what it offers on traditional web browsers, as the user experience is quite
different. For further information, a book such as Handheld Usability is a great
read.
9. 3-d push button effect
Back in the early days of the web, 3-d buttons that appeared to become pushed
in when moused over were all the rage. At that time, this could only be achieved
through images and JavaScript, but now with the advent of CSS we can go all
retro and re-create this effect:
The main CSS commands you'll need are:
a {
display: block;
border: 1px solid;
border-color: #aaa #000 #000 #aaa;
width: 8em;
background: #fc0;
}
a:hover
{
position: relative;
top: 1px;
left: 1px;
border-color: #000 #aaa #aaa #000;
}
Aside from these commands, you can insert any other commands to achieve the
desired presentation effect - the only limit is your imagination!
10. Same navigation code on every page
Most websites highlight the navigation item of the user's location in the website,
to help users orientate themselves. This is a fundamental requirement for basic
usability, but can be a pain as you'll need to tweak the HTML code behind the
navigation for each and every page. So can we have the best of both worlds?
Is it possible to have the navigation highlighted on every page, without having
to tweak the HTML code on each and every page? Of course it is...
First of all, you'll need to assign a class to each navigation item:
<ul>
<li><a href="#" class="home">Home</a></li>
<li><a href="#" class="about">About us</a></li>
<li><a href="#" class="contact">Contact us</a></li>
</ul>
You'll then need to insert an id into the <body> tag. The id should be
representative of where users are in the site and should change when users move
to a different site section. When in ‘Home’ it should read <body
id="home">, in ‘About Us’ it should be <body id="about">
and in ‘Contact Us’ <body id="contact">.
Next, you create a new CSS rule:
#home .home, #about .about, #about .about
{
commands for highlighted navigation go here
}
This basically creates a rule that only takes effect when class="home"
is contained within id="home", and when class="about" is
in id="about" and class="contact" is in id="contact".
These situations will only occur when the user is in the appropriate site section,
seamlessly creating our highlighted navigation item.
This article was written by Trenton Moss. (Webcredible
)
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