Sunday 24th of September 2017 01:30:32 AM

Style Guide

CSS: Style Sheet Guidelines (1)

According to its creators at W3C, Cascading Style Sheets “is a simple mechanism for adding style (e.g. fonts, colors, spacing) to Web documents.” Let's expand that definition to see what it means for Web designers and developers:

  1. CSS is a standard layout language for the Web—one that controls colors, typography, and the size and placement of elements and images.
  2. Though precise and powerful, CSS is easy to author by hand.
  3. It is bandwidth–friendly technology: a single 10K CSS document can control the appearance of an entire website, comprising thousands of pages and hundreds of megabytes. (For an example, see the Sophisticated Style Sheet on page 2.)
  4. CSS is intended by its creators (W3C) to replace HTML table-based layouts, frames, and other presentational hacks.
  5. CSS, together with other web standards such as XHTML, helps us separate style from content, making the Web more accessible, and opening it up to more powerful applications and technologies to come.

Laying out pages with CSS instead of HTML tables—or using CSS simply to replace redundant, non–standard HTML hacks, such as invalid extensions to the <font> tag or the <body> tag—provides the following benefits:

  1. Conserve bandwidth (less markup for visitors to download)
  2. previous status. Thus, if an image (which is ordinarily treated as aninline element) is floated, it becomes a block-level element. Thisblock-level status helps explain why when an element is floated,other content flows around it.

    Remember that if you float atextelement, its width will tend toward zero. This is exactly theopposite of the normal horizontal rules, wherewidth is increased until the seven properties

  3. Reduce design/development time
  4. Reduce updating and maintenance time
  5. Increased accessibility (fewer, or no, HTML tables; no invalid junk markup)
  6. Adhere to W3C recommendations, improving interoperability and ensuring greater longevity (sites will not become obsolete)
  7. Better, more professional appearance (line–height, borders, padding, margins)
  8. Increased readability (line–height, borders, padding, margins)
  9. More easily transition in future to more powerful standards such as XML (because page content no longer contains junk markup)

On the next page, we explore the basics of CSS and its recommended usage at NYPL. »

« CSS Section Index | CSS Guidelines 2 »

P.roof {border-top: dashed;}

Another thing to note is that since each of these "border-side" properties applies only to a specific side, there isn't any possibility of value replication -- it wouldn't make any sense. There can only be one of each type of value: that is, only one width value, only one color value, and only one border style. So don't try to declare more than one value type:

8.4.2.2. Adding box properties

As we're aware from previous discussions, padding, margins, and borders may all be applied to inline nonreplaced elements, and they don't influence the line-height at all. If we were to apply some borders to a SPAN element without any margins or padding, we'd get results such as that shown in