Written by VR Sunday, 06 March 2011 18:23
Begun as a separate working group effort,Cascasing Style Sheets-Positioning offers much more in the way of interactively:more of the D in DHTML.The basic notation of CSS-P is that an element or group of elements can be placed in its own plane above the main document.The element lives in its own transparent layer,so it can be hidden,shown precisely positioned and moved around the page with out disturbing the other content or the layout of the document.For the first time,HTML elements can even overlap each other.
A script can maka element fly around the page or it can allow the user to drag elements around the page.Content can pop up out of now where or expand to let the viewer see more content all without reloading the page or contacting the server.
As an ass-on to the CSS1 effort CSS-P functionality uses a syntax that simply extends the CSS1 vocabulary.CSS-P rules are embedded in document the same way that CSS1 rules are embedded.The W3C work on CSS-P wasn't as far along as CSS1 was when Navigator 4 had to be put to bed.Moreover,Netscape had been lobbying the standards bodies to adopt a different technique for handling content positioning involving both a new HTML tag and a scriptable object.
Written by VR Sunday, 06 March 2011 18:16
In the next generation Cascading Style Sheets Level 2 the work from the CSS-P group is being blended with the other style sheet specifications.Therefore,with the release of CSS2,there is no separate CSS-P specification.CSS2 also greatly expands on CSS1 by supporting style sheet functionality for a lot of the advanced work in HTML.Thus you 'll find new style attributes for electronic speech and more attributes designed to remove style burdens from HTML element attributes.CSS2 is more recent than either Version 4 browser.Navigator 4 incorporates nothing yet from CSS2 and Internet Explorer 4 has only a smattering of CSS2 attributes built in.A lot of the new items added to CSS2 are optional,so there is no reason to expect a 100% implementation in any browser in the future.
Last Updated on Sunday, 06 March 2011 18:22 Written by VR Sunday, 06 March 2011 17:56
The Cascading Style Sheets Level 1 recommendation lets authors define style rules that are applied to HTML elements.A rule may apply to a single element a related group of elements or all elements of a particular type.Style rules influence the rendering of elements,including their color,alignment,border,margins and padding between borders and the content.Style rules can also control specialty items,such as whether an OL element uses letters or roman numerals as item markers.CSS1 defines a full defines a full syntax for assigning style attributes to rules.
CSS frees you from the tyranny of the pixel and the arbitrary way that each browser measures fonts and other values.Font sizes can be specified in real point sizes instead of the absurd 1 through 7 relative scale of HTML.If you want a paragraph or a picture indented from the left margin,you can do so with the precision of ems or picas,instead of relying on hokey arrangements of tables and transparent images.
Many of the style specifications that go into CSS rules derive their inspiration from existing HTML tag attributes that control visual aspects of elements.In some cases,style sheet rules even supplant entire HTML elements.For example in the world of CSS font changes within a paragraph are not done with FONT tags.Instead a style sheet rule sets the font and the style rule is assigned to structural HTML elements that surround the affected content.
On their own style sheets as described in the CSS1 specification are not dynamic.They simply set rules that are followed as a page loads.But under script control,there is the possibility of changing a style rule after a page has loaded.
Written by VR Sunday, 06 March 2011 15:01
In some DHTML applications,it is not always efficient to have target elements process events.For example,if you have a page that allows users to select and drag elements around the page,it is quite possible that one centralized function can handle that operation for all elements.Rather than define event handlers for all of those elements,it is better to have the mouse-related events go directly to an object or elements that has scope over all the draggable elements.In other words,one event handler can do the job of a dozen.For this kind of treatment to work,events must be able to propagate through the hierarchy of objects or elements in the document.
The differences in the event models between Navigators4 and Internet Explorer 4 are most evident in the way that an event passes through the document hierarchy after it fires.Events literally travel in opposite directions in the two browsers.Navigator 4 events trickle down through the object hierarchy to the intended target object while IE 4 events bubble up from the target element through the element containment hierarchy.
Written by VR Sunday, 06 March 2011 14:49
The purpose of the visibility attribute is obvious,it makes an element visible or hidden.Unless the element is under script control,however it is unlikely that you would bother setting the attribute's value.There is rarely a need to load a normally visible HTML element in to page as hidden ,unless you also have a script that changes its state as the user visits the page-perhaps in response to mouse clicks or a times event.
It is however,important to understand the different between setting a positionable element's visibility attribute and setting the CSS display attribute to none.When a positionable element is set to be hidden,the space occupied by the element-whether it be a position in the stacking order or the location for flowed content set off as a relative positioned element does not go away.If you hide a relative positioned element that happens to be an emphasized chunk of text within a sentence,the rest of the sentences text does not close up when the positioned portion is hidden.
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