css

Selector syntax

Posted on by Rajesh Odayanchal

A simple selector is either a type selector or universal selector followed immediately by zero or more attribute selectors, ID selectors, or pseudo-classes, in any order. The simple selector matches if all of its components match.

A selector is a chain of one or more simple selectors separated by combinators. Combinators are: whitespace, “>”, and “+”. Whitespace may appear between a combinator and the simple selectors around it.

The elements of the document tree that match a selector are called subjects of the selector. A selector consisting of a single simple selector matches any element satisfying its requirements. Prepending a simple selector and combinator to a chain imposes additional matching constraints, so the subjects of a selector are always a subset of the elements matching the rightmost simple selector.

One pseudo-element may be appended to the last simple selector in a chain, in which case the style information applies to a subpart of each subject.

CSS Design Principles

Posted on by Rajesh Odayanchal

CSS design principles

CSS3 as CSS2 and CSS1 before it, is based on a set of design principles:

  • Forward and backward compatibility. CSS2 user agents will be able to understand CSS1 style sheets. CSS1 user agents will be able to read CSS2 style sheets and discard parts they don’t understand. Also, user agents with no CSS support will be able to display style-enhanced documents. Of course, the stylistic enhancements made possible by CSS will not be rendered, but all content will be presented.

  • Complementary to structured documents. Style sheets complement structured documents (e.g., HTML and XML applications), providing stylistic information for the marked-up text. It should be easy to change the style sheet with little or no impact on the markup.

  • Vendor, platform, and device independence. Style sheets enable documents to remain vendor, platform, and device independent. Style sheets themselves are also vendor and platform independent, but CSS2 allows you to target a style sheet for a group of devices (e.g., printers).

  • Maintainability. By pointing to style sheets from documents, webmasters can simplify site maintenance and retain consistent look and feel throughout the site. For example, if the organization’s background color changes, only one file needs to be changed.

  • Simplicity. CSS2 is more complex than CSS1, but it remains a simple style language which is human readable and writable. The CSS properties are kept independent of each other to the largest extent possible and there is generally only one way to achieve a certain effect.

  • Network performance. CSS provides for compact encodings of how to present content. Compared to images or audio files, which are often used by authors to achieve certain rendering effects, style sheets most often decrease the content size. Also, fewer network connections have to be opened which further increases network performance.

  • Flexibility. CSS can be applied to content in several ways. The key feature is the ability to cascade style information specified in the default (user agent) style sheet, user style sheets, linked style sheets, the document head, and in attributes for the elements forming the document body.

  • Richness. Providing authors with a rich set of rendering effects increases the richness of the Web as a medium of expression. Designers have been longing for functionality commonly found in desktop publishing and slide-show applications. Some of the requested rendering effects conflict with device independence, but CSS2 goes a long way toward granting designers their requests.

  • Alternative language bindings. The set of CSS properties described in this specification form a consistent formatting model for visual and aural presentations. This formatting model can be accessed through the CSS language, but bindings to other languages are also possible. For example, a JavaScript program may dynamically change the value of a certain element’s ‘color’ property.

  • Accessibility. Several CSS features will make the Web more accessible to users with disabilities:

    • Properties to control font appearance allow authors to eliminate inaccessible bit-mapped text images.
    • Positioning properties allow authors to eliminate mark-up tricks (e.g., invisible images) to force layout.
    • The semantics of !important rules mean that users with particular presentation requirements can override the author’s style sheets.
    • The new ‘inherit’ value for all properties improves cascading generality and allows for easier and more consistent style tuning.
    • Improved media support, including media groups and the braille, embossed, and tty media types, will allow users and authors to tailor pages to those devices.
    • Aural properties give control over voice and audio output.
    • The attribute selectors, ‘attr()’ function, and ‘content’ property give access to alternate content.
    • Counters and section/paragraph numbering can improve document navigability and save on indenting spacing (important for braille devices). The ‘word-spacing’ and ‘text-indent’ properties also eliminate the need for extra whitespace in the document.

Rounded Corners

Posted on by Rajesh Odayanchal

When New WordPress started using this i though you know Internet Explorer is definitely out now when i’m doing some css work that needs rounded corners I’m mostly using only this technique because buyers are ok with it although it’s just for FireFox and Safari. And since most of people still don’t know about this i figured it’s good thing to share.

Of course i’m talking about Border-radius property for FireFox and Safari 3 (only). And here are some nice examples how to use it.

#box { background: #eee; border: 1px solid #ccc; padding: 15px; -moz-border-radius: 10px; -webkit-border-radius: 10px; }

And of course you don’t have to make all corners rounded, it can be just top left etc, so the code goes like this (small not, for example you can’t make rounded corners on images and stuff like that)

* -moz-border-radius-topleft and -webkit-border-top-left-radius
* -moz-border-radius-topright and -webkit-border-top-right-radius
* -moz-border-radius-bottomleft and -webkit-border-bottom-left-radius
* -moz-border-radius-bottomright and -webkit-border-bottom-right-radius

100% height model css?

Posted on by Rajesh Odayanchal

I had been looking around for a way to accomplish fixed header and footer on a website when scrolling, and somehow i haven’t got it right with background attachment: fixed, neither i got it with absolute position…

I have a main Div called wrapper, inside there are three main Divs: header, content and footer, and each one of them has sub Divs inside for the content of each one. So the structure goes something like this in general terms:

body[

[ Div:wrapper
Div:Header
Div:top-banner
Div:Menu
Div:Buttons
]
[Div:Content]

[Div:Footer
Div:bottom-banner
]
]

is there any way to accomplish that the header and footer remain “locked” at the top and bottom of the browser window and only the content scrolls down.

See Here is the proper solution:

html, body {
height: 100%;
}

body {
any other styles;
}

#container {
min-height: 100%;
other styles;
}
* html #container {height: 100%;}/*IE6*/

this way, your page start out 100% but can grow bigger as content demands.

The benefits of Web Standards to your visitors, your clients and you!

Posted on by Rajesh Odayanchal

  1. The Web Standards
  2. What are Web Standards about?
  3. A mindset change
  4. Semantically correct markup
  5. What is valid code?
  6. What is accessible code?
  7. Why use CSS to separate content from presentation?
  8. A CSS based site in action
  9. How do your VISITORS benefit from Web Standards?
  10. How do your CLIENTS benefit from Web Standards?
  11. How do YOU benefit from Web Standards?
  12. What are the downsides
  13. How do you achieve Web Standards?
  14. Conclusion
  15. Web Standards resources

CSS font shorthand rule

Posted on by Rajesh Odayanchal

When styling fonts with CSS you may be doing this:
font-size: 1em;
line-height: 1.5em;
font-weight: bold;
font-style: italic;
font-variant: small-caps;
font-family: verdana,serif;

There’s no need though as you can use this CSS shorthand property:
font: 1em/1.5em bold italic small-caps verdana,serif

Much better! Just a couple of words of warning: This CSS shorthand version will only work if you’re specifying both the font-size and the font-family. Also, if you don’t specify the font-weight, font-style, or font-varient then these values will automatically default to a value of normal, so do bear this in mind too.

Why tables for layout is stupid:

Posted on by Rajesh Odayanchal

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.

    IE and width & height issues

    Posted on by Rajesh Odayanchal

    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 command5. Non-IE browsers will read through the second one and will override the values from the first rule because this CSS rule is more specific, and CSS rules that are more specific always override those that are less specific.

    Minimum width for a page

    Posted on by Rajesh Odayanchal

    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

    under the tag, as we can’t assign a minimum width to the :

    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”);
    }