html - z-index Not Working with Absolute Position - Stack Overflow
In order to apply the z-index property to an element, you must first apply a position value of relative, absolute, or fixed. The Z-Index CSS Property: A Comprehensive Look . Here are the same boxes with position: relative added to each, and their z-index values maintained: . z- index to enhance the site's template, weaving year and date. This is because the Z-Index does not work with static positioning. Z-Index requires an element's positioning to be either fixed, relative, or absolute. Judging .
When painting pixels onto the screen, the browser makes sure that the pixels that are closest to the canvas or farthest from us get painted first.
By default, all elements have a z-index of 0, and the browser paints in DOM order. However, z—index actually gives us fine-grained control over when an element is painted.
The first caveat attached to z-index is that it must be on a positioned element in order to take effect. A stacking context involves an HTML node and all of its children. The HTML element at the root level of the stacking context can be referred to as the stacking root.
Here are a few ways that you can designate an element as the root of a new local stacking context: Setting an opacity that is less than 1 on an element. Using transform or will-change on an element.
How CSS works: Creating layers with z-index
If you want to see a more comprehensive list of ways to create new stacking contexts, check out this article on MDN. Notice anything strange going on with the layers?
First off, why is blue-child-2 below anything else? It has a z-index of one million, so it should be on top, right? Using the clearfix technique for example, Dan Cederholm helped coin the class name group. The group class name can then be applied to any parent element needing to contain floats. When trying to use the clearfix technique with other: In the examples above, the clearfix styles would not live under the box-set class.
Instead, the class of group would need to be added to the parent element containing the floats. Position Property Occasionally you need more control over the position of an element, more than a float can provide, in which case the position property comes into play.
The position property accepts five different values, each of which provide different ways to uniquely position an element. Furthermore, elements will be positioned as intended, with their default behaviors.
Detailed Positioning - Learn to Code Advanced HTML & CSS
In the demonstration below, all the boxes are stacked one on top of the other as they are block level elements and are not floated in any specific direction. Position Relative The relative value for the position property is very similar to that of the static value. The primary difference is that the relative value accepts the box offset properties top, right, bottom, and left.
These box offset properties allow the element to be precisely positioned, shifting the element from its default position in any direction.
How Box Offset Properties Work The box offset properties, top, right, bottom, and left, specify how elements may be positioned, and in which direction. These offset properties only work on elements with a relative, absolute, or fixed positioning value. For relatively positioned elements, these properties specify how an element should be moved from its default position. For example, using a top value of 20px on a relatively positioned element will push the element 20 pixels down from where it was originally placed.
Switching the top value to px will instead pull the element 20 pixels up from where it was originally placed. For elements using absolute or fixed positioning these properties specify the distance between the element and the edges of its parent element.
For example, using a top value of 20px on an absolutely positioned element will push the element 20 pixels down from the top of its relatively positioned parent. Switching the top value to px will then pull the element 20 pixels up from the top of its relatively positioned parent.
While the relative position does accept box offset properties the element still remains in the normal, or static, flow of the page. In this case other elements will not impede on where the relatively positioned element was originally placed.
Z-Index is not voodoo bro – codeburst
Additionally, the relatively positioned element may overlap, or underlap, other elements without moving them from their default position. In the demonstration below you will notice that the elements are still stacked on top of one another, however they are shifted from their default positions according to their individual box offset property values.
These values cause the boxes to overlap one another, yet do not push each other in different directions. When an element is positioned relatively the surrounding elements will observe the relatively positioned elements default position. In the event that the top and bottom box offset properties are both declared on a relatively positioned element, the top properties will take priority.
Additionally, if both the left and right box offset properties are declared on a relatively positioned element, priority is given in the direction in which the language of the page is written. For example, in English pages the left offset property is given priority, and for Arabic pages the right offset property is given priority. Position Absolute Absolutely positioned elements accept box offset properties, however they are removed from the normal flow of the document.
Upon removing the element from the normal flow, elements are positioned directly in relation to their containing parent whom is relatively or absolutely positioned. Should a relatively or absolutely positioned parent not be present, the absolutely positioned element will be positioned in relation to the body of the page.
Using absolutely positioned elements and specifying both vertical and horizontal offset properties will move the element with those property values in relation to its relatively positioned parent. For example, an element with a top value of 50px and a right value of px will position the element 50 pixels down from the top of its relatively positioned parent and pixels in from the right of its relatively positioned parent.