We encourage you to work through this section carefully, and check that you understand the concepts before moving on.At some point, you will be working on a project and you will find that the CSS you thought should be applied to an element is not working. You wouldn’t need to rely upon !important rules then, or any more specific selectors.Hey Chris, you wrote “children” but meant “descendants”. sorry for myself because i see here now!thanks a lot!Really cool article. Pour appeler une classe dans le code HTML, il suffit de rajouter un attribut Il est possible de ne pas préciser de balise, auquel cas la classe pourra être utilisée 19 janvier 2014 on CSS, Débutant, Bases CSS. Thanks.Just a thought, I believe a more clear (but not really real) example would be:Just a thought, I believe a more clear (but not really real) example would be:And I say that because .box class in Demo could is, in fact, the div element. To some of you, that top selector may seem like a mistake, but it’s actually a quite useful selector. We've not covered selectors in detail yet, but you can find details of each selector on the MDN Before we move on, let's look at an example in action.So what's going on here? - But really, don't use it if you can avoid it.Finally, it is also useful to note that the importance of a CSS declaration depends on what stylesheet it is specified in — it is possible for users to set custom stylesheets to override the developer's styles, for example the user might be visually impaired, and want to set the font size on all web pages they visit to be double the normal size to allow for easier reading.Conflicting declarations will be applied in the following order, with later ones overriding earlier ones:It makes sense for web developers' stylesheets to override user stylesheets, so the design can be kept as intended, but sometimes users have good reasons to override web developer styles, as mentioned above — this can be achieved by using We have covered a lot in this article, but can you remember the most important information? You can find some further tests to verify that you've retained this information before you move on — see If you understood most of this article, then well done — you've started getting familiar with the fundamental mechanics of CSS.
not seeing how to use #id.class in ie6 using conditionals off the top of my head. This comment thread is closed. We'd advise that you return to this article a few times as you continue through the course, and keep thinking about it.Refer back here if you start to come across strange issues with styles not applying as expected. Sign in to enjoy the benefits of an MDN account. first will be red. CSS classes¶ In the field named “CSS class names”, the administrator may specify arbitrary CSS classes separated by commas. La définition des classes est aussi simple que celles des styles. Essentially a value in points is awarded to different types of selectors, and adding these up gives you the weight of that particular selector, which can then be assessed against other potential matches.The amount of specificity a selector has is measured using four different values (or components), which can be thought of as thousands, hundreds, tens and ones — four single digits in four columns:The following table shows a few isolated examples to get you in the mood. Pour cela, il suffit dans votre code CSS d'écrire les classes les unes à côté des autres séparées par un espace: la première sera parente de la deuxième, qui sera parente de la troisième, etc... à condition que chacune soit imbriquée dans l'autre au sein de votre code HTML Thanks.That is a great review of selectors and the differentiations between them. `#header.callout` is the element with both id=”header” and class=”callout”, while `#header .callout` is child with class=”callout” of the element with id=”header”.Actually #header .callout concerns the element(s) with the class = callout which is a/are descendant(s) (not child(ren)) of the element wit id=header.Same as Chris – you’ve got the descriptions the wrong way round..Wow! This small difference makes a huge difference in what it does.
Later ones overrule earlier ones:We will look at these to see how browsers figure out exactly what CSS should be applied.We have already seen how source order matters to the cascade. or the bottom, for that matter.hrm. First of all, we are only interested in the first seven rules of this example, and as you'll notice, we have included their specificity values in a comment before each one.A more accurate way to evaluate specificity would be to score the specificity levels individually starting from highest and moving on to lowest when necessary. One of those is overriding styles easily.The second targets the same element, but overrides the color, instead of having to use:or perhaps prefacing the selector with something even more specific.More useful is multiple classes and using them in the “object oriented” css style that is all the rage lately. This can seem like a set of tricky concepts to understand.