Can i use css3 yet

This process usually involves a lot of give and take with the web development community, standards organizations like W3C , and browser developers.

Newer properties often exist for some time before they can be reliably used on production sites. This happens for various reasons:. To allow use of a CSS specification that is not fully implemented in a browser or in early implementation, we use what are known as CSS Vendor Prefixes. Up until now, most of the CSS you've learned is fully supported in all browsers.

For newer properties, from CSS3 and later, that's not always going to be the case. Here we preload our CSS and JavaScript files so they will be available as soon as they are required for the rendering of the page later on. For example:. Using as to specify the type of content to be preloaded allows the browser to:. Many different content types can be preloaded. The possible as attribute values are:. Note: video preloading is included in the Preload spec, but is not currently implemented by browsers.

Note: There's more detail about these values and the web features they expect to be consumed by in the Preload spec — see link element extensions. Also note that the full list of values the as attribute can take is governed by the Fetch spec — see request destinations. This is especially useful when preloading resources — the browser will use the type attribute value to work out if it supports that resource, and will only download it if so, ignoring it if not.

Suppose we wanted the hues and angle in a conic gradient to vary based on the time of day. The same JavaScript would work for the mouse, and we could add a bit of JavaScript that sets a CSS variable with the current hour 0—23 :.

CSS variables also make it possible to reuse and customize CSS code, since they make encapsulation possible. Its simplified CSS code looks like this:.

Say we want different colored buttons for different actions, such as a red button for a dangerous action. We could support a. In fact, theming third-party CSS code used to mean becoming intimately familiar with its internal structure, and changing third-party code required similarly extensive changes in the theming code.

Now CSS custom properties can serve as an API of sorts: dramatically changing the underlying style with custom properties alone. Circling back to our button example, suppose we want to add a transition for a smoother hover effect. We also want the new background color to grow inward from the border, instead of the default fade we get when transitioning between two background colors. To accomplish this, we need to fake the background with an inset box-shadow :.

If we had needed to override the CSS for theming, then our theming code would have broken. This ability—not saving a few characters or time on maintenance—is the true value of custom properties. They enable us to share code that can be reused and customized by other developers while still allowing us to completely change its internal structure. Typically, style guides start from one or a few base accent colors, from which the rest of the palette is drawn.

Using variables for only the base colors is more efficient than having to manually tweak each color variation. In the meantime, instead of defining our base color as one variable, we need to use separate variables for the color components. Out of the color syntaxes currently available to CSS, hsl tends to work better for creating color variations until we get lch , which is far superior due to its wider range and perceptual uniformity.

We can use these variables throughout our CSS or create new variations on the fly. When CSS variables are used to hold data, their default behavior—inheritance—is desired: We define the variables on the root element and can override them on a subtree by redefining them.

But inheritance often gets in the way. Consider the following example, which uses a variable to apply a subtle glow with a predefined color, offset, and blur radius, but with variable spread:. See this corrected effect in action on Dabblet. To fix it, we need to disable inheritance by adding --subtle-glow: initial to the first rule.

Custom properties are a powerful and well-supported addition to CSS, and their true potential has yet to be fully explored. The following rule hides all elements for which the value of the "lang" attribute is "fr" i. The following rule will match for values of the "lang" attribute that begin with "en", including "en", "en-US", and "en-cockney":. Similarly, the following aural style sheet rules allow a script to be read aloud in different voices for each role:.

Matching takes place on attribute values in the document tree. Default attribute values may be defined in a DTD or elsewhere, but cannot always be selected by attribute selectors. Style sheets should be designed so that they work even if the default values are not included in the document tree.

More precisely, a UA may, but is not required to, read an "external subset" of the DTD but is required to look for default attribute values in the document's "internal subset.

Depending on the UA, a default attribute value defined in the external subset of the DTD might or might not appear in the document tree.

Note that, typically, implementations choose to ignore external subsets. To catch all cases, the attribute selector for the default value must be dropped:. Care has to be taken that all property declarations that are to apply only to the default case are overridden in the non-default cases' style rules.

Thus, for HTML, div. The attribute value must immediately follow the "period". UAs may apply selectors using the period. One such example of namespace specific knowledge is the prose in the specification for a particular namespace e.

Given these rules, the first H1 instance below would not have green text, while the second would:. For example, the following rule matches any P element whose "class" attribute has been assigned a list of space-separated values that includes "pastoral" and "marine":. CSS gives so much power to the "class" attribute, that authors could conceivably design their own "document language" based on elements with almost no associated presentation such as DIV and SPAN in HTML and assigning style information through the "class" attribute.

Authors should avoid this practice since the structural elements of a document language often have recognized and accepted meanings and author-defined classes may not. Note: If an element has multiple class attributes, their values must be concatenated with spaces between the values before searching for the class. As of this time the working group is not aware of any manner in which this situation can be reached, however, so this behavior is explicitly non-normative in this specification.

What makes attributes of type ID special is that no two such attributes can have the same value; whatever the document language, an ID attribute can be used to uniquely identify its element.

The ID attribute of a document language allows authors to assign an identifier to one element instance in the document tree. CSS ID selectors match an element instance based on its identifier.

The UA may, e. In the following example, the style rule matches the element that has the ID value "z98y". The rule will thus match for the P element:. In the next example, however, the style rule will only match an H1 element that has an ID value of "z98y". The rule will not match the P element in this example:.

ID selectors have a higher specificity than attribute selectors. In XML 1. However, the cascading order of normal attribute selectors is different from ID selectors. It may be necessary to add an "! If an element has multiple ID attributes, all of them must be treated as IDs for that element for the purposes of the ID selector. This simple model is sufficient for many cases, but some common publishing scenarios may not be possible due to the structure of the document tree.

CSS introduces the concepts of pseudo-elements and pseudo-classes to permit formatting based on information that lies outside the document tree. Neither pseudo-elements nor pseudo-classes appear in the document source or document tree.

Pseudo-classes are allowed anywhere in selectors while pseudo-elements may only be appended after the last simple selector of the selector. Some pseudo-classes are mutually exclusive, while others can be applied simultaneously to the same element. In case of conflicting rules, the normal cascading order determines the outcome. In the following example, the selector matches any P element that is the first child of a DIV element.

The rule suppresses indentation for the first paragraph of a DIV:. The following rule sets the font weight to 'bold' for any EM element that is some descendant of a P element that is a first child:.