As we explained in the previous chapter, HTML
elements enable Web page designers to mark up a document as to its
structure. The HTML specification lists guidelines on how browsers
should display these elements. For example, you can be reasonably
sure that the contents of a strong
element will be displayed bold-faced. Also, you can pretty much
trust that most browsers will display the content of an h1 element using a big font size…
- With
CSS, they can do this by supplying a personal style sheet that
will be merged with the browser’s and the designer’s style sheets. - To write CSS, you don’t need more than a
text editor, but there are many tools available that make it even easier. - This module carries on where CSS first steps left off — now you’ve gained familiarity with the language and its syntax, and got some basic experience with using it, it’s time to dive a bit deeper.
- Some properties, however, don’t inherit and there is always a good
reason why.
The second rule only affects h1 elements in the document and is therefore more
specific. In the example, it is “green,” but it could just as easily be blue, red, yellow, or some other color. The only thing creating this visual change is the use of a different CSS file. Using external Cascading Style Sheet rules and classes to format
a report is described in Formatting a Report With an External Cascading Style Sheet. CSS is used to control the style and layout of multiple web pages all at once.
Use cascading style sheets (CSS) to present page content
At least
bigger than the p element and bigger
than the h2 element. But beyond trust
and hope, you don’t have any control over how your text appears. CSS is used to define styles for your web pages, including the design, layout, and variations in display for different devices and screen sizes. It was designed to enable the separation of presentation and content, including aspects such as layout, colors, and fonts. This separation improves content accessibility and provides more flexibility and control in the specification of presentation characteristics. CSS works by targeting HTML elements and applying style rules to define how they should be displayed, including properties like color, size, layout, and positioning.
A class may apply to any number of instances of any element. The name cascading comes from the specified priority scheme to determine which declaration applies if more than one declaration of a property match a particular element. The CSS layout cookbook aims to bring together recipes for common layout patterns, things you might need to implement in your sites.
External CSS
However, the user can say that a rule is
very important and it will then override any author or browser
styles. User-agents, or browsers, have basic web development css cascading style sheets that give default styles to any document. Most browsers use actual stylesheets for this purpose, while others simulate them in code.
CSS, or Cascading Style Sheets, offers a flexible way to style web content, with styles originating from browser defaults, user preferences, or web designers. These styles can be applied inline, within an HTML document, or through external .css files for broader consistency. Not only does this simplify web development by promoting reusability and maintainability, it also improves site performance because styles can be offloaded into dedicated .css files that browsers can cache. Before CSS, nearly all presentational attributes of HTML documents were contained within the HTML markup. All font colors, background styles, element alignments, borders, and sizes had to be explicitly described, often repeatedly, within the HTML.
Helpful Links
We have known for years that designers want to develop their
own style sheets. However, we discovered that users, too, want the
option of influencing the presentation of their documents. With
CSS, they can do this by supplying a personal style sheet that
will be merged with the browser’s and the designer’s style sheets. Any conflicts between the various style sheets are resolved by the
browser. Usually, the designer’s style sheet will have the
strongest claim on the document, followed by the user’s, and then
the browser’s default.
External style sheets can be referenced with a full URL or with a path relative to the current web page. The last properties, font-variant and line-height, haven’t been widely supported in browsers up to now and are therefore not as commonly used yet. This article explains what the cascade is and the order in which CSS declarations cascade, covering cascade layers and origin type. Understanding origin precedence is key to understanding the cascade. It can control the layout of multiple
web pages all at once. Rather than by laboriously going through the document and changing the color for each individual h1 element.
CSS Demo – One HTML Page – Multiple Styles!
This module looks at the cascade and inheritance, all the selector types we have available, units, sizing, styling backgrounds and borders, debugging, and lots more. As a general rule, properties in CSS inherit from
parent to child elements as described in the previous examples. Some properties, however, don’t inherit and there is always a good
reason why. We will use the background property (described in Chapter 11) as an
example of a property that doesn’t inherit.
Classes are described in What Are Cascading Style Sheet Rules and Classes?. CSS is a critical tool for web designers and is widely supported by all modern web browsers. Please note, though, that the use of CSS does not in itself make a Web page accessible. The most critical consideration is the use of valid, semantic (X)HTML. In fact, any page that uses styles should be usable with the styles disabled.
“styles.css”:
CSS lets authors move much of that information to another file, the style sheet, resulting in considerably simpler HTML. And additionally, as more and more devices are able to access responsive web pages, different screen sizes and layouts begin to appear. Customizing a website for each device size is costly and increasingly difficult. The modular nature of CSS means that styles can be reused in different parts of a site or even across sites, promoting consistency and efficiency. In the last set of examples you saw that the text color of the
links turned blue without that being specified in the style sheet.
Using Cascading Style Sheets (CSS) allows developers to separate content from presentation. In other words, with CSS the visual layout of a Web page can be established with style sheets, while the content can be put into HTML. CSS gives developers the ability to change the linear layout of a page — the order of elements on a Web page when all styles and formatting are removed — without altering its visual layout. This is important because the linear reading order of Web content is the order in which screen readers access the content. Another advantage with CSS is that it gives the end user control over the Web page style as well. For example, the user can change the background color or increase the font.
Internal or Embedded CSS:
Values may be keywords, such as “center” or “inherit”, or numerical values, such as 200px (200 pixels), 50vw (50 percent of the viewport width) or 80% (80 percent of the parent element’s width). In CSS, selectors declare which part of the markup a style applies to by matching tags and attributes in the markup itself. CSS is among the core languages of the open web and is standardized across Web browsers according to W3C specifications. Previously, the development of various parts of CSS specification was done synchronously, which allowed the versioning of the latest recommendations. There will never be a CSS3 or a CSS4; rather, everything is now CSS without a version number. You can define classes in a Cascading Style Sheet, and format
a report component by assigning one of these CSS classes to it.
