More advice for the full screen mode.
Sivut toimivat riittävän hyvin MS IE 4.0+, Opera 5.x+, Netscape 6.0+/ vast. Mozilla ja Konqueror 3.x selaimilla. Yleisesti ottaen sivut toimivat parhaiten uusimmilla Opera selaimilla. Sivujen toimivuus vanhemmissa selaimissa on heikko, erityisesti Netscape 4.x kohdalla.

I list below all topic groups, which I have done according to subjects, which they handle. You can return to this topic group by using this menu and the link Table of topic groups on the top of the each page.
Table of topic groupsFront page of CSS-guideGuide pages > 4. What are selectors, classes and id-attributes (introsection)


The basic method on CSS is to apply CSS-properties to elements according to certain principles. The browser must be able to identify elements. Excluding direct style attributes, the browser creates from element identifiers like patterns. That's why in CSS is written about pattern matching. In CSS and and documents, which use CSS must have matching pairs.


If the CSS is defined in external style sheets, they work like some kind databases (they correspond handwritten databases). To get CSS from external style sheets can compare situations, where the content comes from from databases.

CSS makes possible dynamic presentation updating. In embedded CSS the "database" goes with the document. It doesn't fulfil the idea of dynamic presentation updating in other way than the embedded CSS gets from server-side scripts from some external file.

In order to find pairs in the "CSS-database" and the current document, the browser needs so-called selectors. They select, what element or elements get defined CSS-properties. I introduce you in these pages into basic CSS2 selectors (like universal selectors, (element) type selector and class selector) and pattern matching rules.

W3C: CSS2: 5 Selectors; 5.1 Pattern matching[Pw].

In this page I handle also attributes class (class="...") and id (id="..."), because some selectors use them.

Selectors have different weights compared to each others, so they create the cascading order. I handle in this page that aspect introductory. In the page 5[S][Pw] I handle some selectors (first-child What are selectors, classes and id-attributes and adjacent sibling What are selectors, classes and id-attributes), because it is easier to process them in another connection. I collect in that page matching rules. I handle also deeper, in which order the browser should read CSS-definitions (what should be in the practise the cascading order). These two pages belong close to each others and I present matters a little bit different order as the official specification.