You must specify a threshold with at least one of top , right , bottom , or left for sticky positioning to behave as expected. Otherwise, it will be indistinguishable from relative positioning. A positioned element is an element whose computed position value is either relative , absolute , fixed , or sticky.
In other words, it's anything except static. A relatively positioned element is an element whose computed position value is relative. The top and bottom properties specify the vertical offset from its normal position; the left and right properties specify the horizontal offset.
An absolutely positioned element is an element whose computed position value is absolute or fixed. The top , right , bottom , and left properties specify offsets from the edges of the element's containing block.
The containing block is the ancestor relative to which the element is positioned. If the element has margins, they are added to the offset. The element establishes a new block formatting context BFC for its contents.
A stickily positioned element is an element whose computed position value is sticky. It's treated as relatively positioned until its containing block crosses a specified threshold such as setting top to value other than auto within its flow root or the container it scrolls within , at which point it is treated as "stuck" until meeting the opposite edge of its containing block.
Except for the case just described of absolutely positioned elements filling the available space : If both top and bottom are specified technically, not auto , top wins. If both left and right are specified, left wins when direction is ltr English, horizontal Japanese, etc.
Initial value static Applies to all elements Inherited no Computed value as specified Animation type discrete Creates stacking context yes. My adjacent block level elements sit on new lines below me. Because of margin collapsing, we are separated by the width of one of our margins, not both. Nam congue tortor eget pulvinar lobortis. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Nam ac dolor augue.
Pellentesque mi mi, laoreet et dolor sit amet, ultrices varius risus. Nam vitae iaculis elit. Aliquam mollis interdum libero. Sed sodales placerat egestas. Vestibulum ut arcu aliquam purus viverra dictum vel sit amet mi. The child element moves relative to the top of the parent element by px and right of the parent element by 40px. Through these examples, you have seen differences between absolutely and relatively positioned elements.
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Join For Free. Static - this is the default value, all elements are in order as they appear in the document. Relative - the element is positioned relative to its normal position. It is placed some distance above the bottom of the line box to leave room for the descenders of lowercase letters, as shown in Figure 4.
Figure 5 shows some small images with different vertical alignment. When the total width of the inline boxes within a line box is less than the width of the line box itself, the horizontal alignment is controlled by the text-align property.
With text-align:justify , extra space is inserted between the inline boxes, if necessary, to make the content both left- and right-justified. This property applies to block boxes, table cells and inline blocks, and it is inherited—Figure 6 shows the result of applying different values of the text-align property to text inside table cells. An element with position:relative is first laid out just like any static element; block-level or inline.
But then something interesting happens: the generated box is shifted according to the top , bottom , left and right properties. The element still remains where it was in the static document flow. As far as the document flow is concerned, the element has not moved—it is just the end visual result that shows the box being moved.
The key to understanding how these properties work with relative positioning is to realise that they specify the edge that the movement is applied to, not the direction of movement. In other words, the top property shifts the box relative to its top edge, the left property shifts the box relative to its left edge, and so on. The box is shifted away from the specified edge, so top:1em shifts the box 1em away from the top position—in other words, downwards.
Negative numbers shift the box in the opposite direction, so bottomem is the same as top:1em. The rules of CSS say that bottom should be ignored if top is specified. For horizontal movement it depends on the direction property. In a left-to-right environment right is ignored if both left and right are specified; in a right-to-left environment left is ignored. So what use is relative positioning? A word of warning: this example is a bit complex. Below all this there is often a full-width footer, perhaps with a copyright statement or contact information.
Figure 7 shows an example of this type of layout. Figure 7: A typical multiple column layout, with columns sandwiched between a header and a footer. This type of layout used to be created with layout tables back in the Dark Ages the s. Only two options remain: floats or absolute positioning.
The problem with floats is that they only shift to the left or right until they touch the edge of the parent block, or another float. That means floated columns have to appear in the right order in your markup. You may want to have the content before the navigation, for instance, to enhance usability for keyboard navigation and to improve search engine optimisation.
The designers who, fortunately, understand accessibility and device independence have stipulated that the navigation needs to be 12em wide while the sidebar should be 14em. To prevent lines of text from being too long, impeding readability, you need to constrain the layout to a maximum width. In order to prevent overlap in extremely narrow windows you also need to constrain the layout to a minimum width. Within those constraints, the layout should be centred horizontally within the browser window.
We will look at a workaround for that at the end of the example. In fact, you will get odd results throughout this example, even with IE7, because Internet Explorer has many strange rendering bugs.
I will focus on the standards-compliant way to do things in the example, and turn to workarounds at the end. Okay, you have your basic building blocks, but they just appear one after the other.
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