wiki:WF/Sintaxe
 Any HTML element is a possible CSS1 selector. The selector is simply the element that is linked to a particular style. For example, the selector in



P { text-indent: 3em }



is P.

Class Selectors



A simple selector can have different classes, thus allowing the same element to have different styles. For example, an author may wish to display code in a different color depending on its language:



code.html { color: #191970 }

code.css  { color: #4b0082 }



The above example has created two classes, css and html for use with HTML's CODE element. The CLASS attribute is used in HTML to indicate the class of an element, e.g.,



<P CLASS=warning>Only one class is allowed per selector.

For example, code.html.proprietary is invalid.</p>



Classes may also be declared without an associated element:



.note { font-size: small }



In this case, the note class may be used with any element.



A good practice is to name classes according to their function rather than their appearance. The note class in the above example could have been named small, but this name would become meaningless if the author decided to change the style of the class so that it no longer had a small font size.

ID Selectors



ID selectors are individually assigned for the purpose of defining on a per-element basis. This selector type should only be used sparingly due to its inherent limitations. An ID selector is assigned by using the indicator "#" to precede a name. For example, an ID selector could be assigned as such:



1.svp94O { text-indent: 3em }



This would be referenced in HTML by the ID attribute:



<P ID=svp94O>Text indented 3em</P>



Contextual Selectors



Contextual selectors are merely strings of two or more simple selectors separated by white space. These selectors can be assigned normal properties and, due to the rules of cascading order, they will take precedence over simple selectors. For example, the contextual selector in



P EM { background: yellow }



is P EM. This rule says that emphasized text within a paragraph should have a yellow background; emphasized text in a heading would be unaffected.

Declarations

Properties



A property is assigned to a selector in order to manipulate its style. Examples of properties include color, margin, and font.

Values



The declaration value is an assignment that a property receives. For example, the property color could receive the value red.

Grouping



In order to decrease repetitious statements within style sheets, grouping of selectors and declarations is allowed. For example, all of the headings in a document could be given identical declarations through a grouping:



H1, H2, H3, H4, H5, H6 {

  color: red;

  font-family: sans-serif }



Inheritance



Virtually all selectors which are nested within selectors will inherit the property values assigned to the outer selector unless otherwise modified. For example, a color defined for the BODY will also be applied to text in a paragraph.



There are some cases where the inner selector does not inherit the surrounding selector's values, but these should stand out logically. For example, the margin-top property is not inherited; intuitively, a paragraph would not have the same top margin as the document body.

Comments



Comments are denoted within style sheets with the same conventions that are used in C programming. A sample CSS1 comment would be in the format:



/* COMMENTS CANNOT BE NESTED */