Web colors - Knowledge

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readers are better served by contrast ratios below the maximum. The recommendations they refer to of off-black (#0A0A0A) on off-white (#FFFFE5) and black (#000000) on creme (#FAFAC8) have contrast ratios of 11.7:1 and 20.3:1 respectively. Among their other color pairs, brown (#282800) on dark green

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The following table shows all of the "web-safe" colors. One shortcoming of the web-safe palette is its small range of light colors for webpage backgrounds, whereas the intensities at the low end of the range, such as the two darkest, are similar to each other, making them hard to distinguish. Values

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Designers were encouraged to stick to these 216 "web-safe" colors in their websites because there were a lot of 8-bit color displays when the 216-color palette was developed. David Lehn and Hadley Stern discovered that only 22 of the 216 colors in the web-safe palette are reliably displayed without

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for more details). The remainder gives the second hexadecimal digit. For instance, the RGB value 58 (as shown in the previous example of hex triplets) divides into 3 groups of 16, thus the first digit is 3. A remainder of ten gives the hexadecimal number 3A. Likewise, the RGB value 201 divides into

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in the "HTML4 color keywords" section, which was renamed as "Basic color keywords". In the same reference, the "SVG color keywords" section, was renamed "Extended color keywords", after starting out as "X11 color keywords" in an earlier working draft. The working draft for the level 4 color module

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For example, consider the color where the red/green/blue values are decimal numbers: red=123, green=58, blue=30 (a hardwood brown color). The decimal numbers 123, 58, and 30 are equivalent to the hexadecimal numbers 7B, 3A, and 1E, respectively. The hex triplet is obtained by concatenating the six

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There were various attempts to make a "standard" color palette. A set of colors was needed that could be shown without dithering on 256-color displays; the number 216 was chosen partly because computer operating systems customarily reserved sixteen to twenty colors for their own use; it was also

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The list of colors was presented as if it had special properties that render it immune to dithering, but on 256-color displays applications could actually set a palette of any selection of colors that they chose, dithering the rest. These colors were chosen specifically because they matched the

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RGB values are usually given in the 0–255 range; if they are in the 0–1 range, the values are multiplied by 255 before conversion. This number divided by sixteen (integer division; ignoring any remainder) gives the first hexadecimal digit (between 0 and F, where the letters A to F represent the

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In the mid-1990s, many displays were only capable of displaying 256 colors, dictated by the hardware or changeable by a "color table". When a color was found (e.g., in an image) that was not available, a different one had to be used. This was done by either using the closest color or by using

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An abbreviated, three (hexadecimal)-digit or four-digit form can be used, but can cause errors if software or maintenance scripts are only expecting the long form. Expanding this form to the six-digit form is as simple as repeating each digit: 09C becomes 0099CC as presented on the following

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If any one of the three color values is less than 10 hex (16 decimal), it must be represented with a leading zero so that the triplet always has exactly six digits. For example, the decimal triplet 4, 8, 16 would be represented by the hex digits 04, 08, 10, forming the hex triplet 040810.

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for a total of 140 names that were recognized by Internet Explorer (IE) 3.0 and Netscape Navigator 3.0. Blooberry.com notes that Opera 2.1 and Safari 1 also included Netscape's expanded list of 140 color names, but later discovered 14 names not included with Opera 3.5 on Windows 98.

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where the palette is shared between applications, smaller color cubes (5×5×5 or 4×4×4) were allocated by browsers—the "web-safe" colors would dither on such systems. Different results were obtained by providing an image with a larger range of colors and allowing the browser to

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recommendation, dark brown (#1E1E00) on light green (#B9B900) has a contrast ratio of 4.54:1 and blue (#00007D) on yellow (#FFFF00) has a contrast ratio of 11.4:1. The colors named in the report use different color values than the web colors of the same name.

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Either no colors should be specified (to invoke the browser's default colors), or both the background and all foreground colors (such as the colors of plain text, unvisited links, hovered links, active links, and visited links) should be specified to avoid

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The list of web "X11 colors" from the CSS3 specification, along with their hexadecimal and decimal equivalents, is shown below. Compare the alphabetical lists in the W3C standards. This includes the common synonyms: aqua (HTML4/CSS 1.0 standard name) and

470:. One byte represents a number in the range 00 to FF (in hexadecimal notation), or 0 to 255 in decimal notation. This represents the least (0) to the most (255) intensity of each of the color components. Thus web colors specify colors in the 574:

This shorthand form reduces the palette to 4,096 colors, equivalent of 12-bit color as opposed to 24-bit color using the whole six-digit form (16,777,216 colors). This limitation is sufficient for many text-based documents.

3367:, picking the operating system's highlighted text color, or the background color for tooltip controls. This enables web authors to style their content in line with the operating system of the user agent. The 1413:. A particular browser may not recognize all of these colors, but as of 2005, all modern, general-use, graphical browsers support the full list of colors. Many of these colors are from the list of 6426: 430:

vary in the fidelity with which they represent the specified colors. More advanced user agents use color management to provide better color fidelity; this is particularly important for

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triplet: each component (red, green, and blue) takes one of the six values from the following table (out of the 256 possible values available for each component in full 24-bit color).

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by making one or more of the red, green and blue components negative or greater than 100%, so the color space is theoretically an unbounded extrapolation of sRGB similar to

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The list of colors shipped with the X11 product varies between implementations and clashes with certain of the HTML names such as green. X11 colors are defined as simple

466:, and other computing applications to represent colors. The bytes represent the red, green, and blue components of the color. The optional fourth byte refers to 595:

12 groups of 16, thus the first digit is C. A remainder of nine gives the hexadecimal number C9. This process is repeated for each of the three color values.

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In CSS 2.1, the color 'orange' (one of the 140) was added to the section with the 16 HTML4 colors as a 17th color. The CSS3.0 specification did not include

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and devices do not support colors. For these displays or blind and colorblind users, Web content depending on colors can be unusable or difficult to use.

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Conversion between number bases is a common feature of calculators, including both hand-held models and the software calculators bundled with most modern

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selected because it allowed exactly six equally spaced shades of red, green, and blue (6 × 6 × 6 = 216), each from 00 to FF (including both limits).

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These 16 were labelled as sRGB and included in the HTML 3.0 specification, which noted they were "the standard 16 colors supported with the Windows

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System Appearance has been dropped, including appearance values & property, and system fonts / extension of the 'font' property shorthand.

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Besides new ways to write colors, it also introduces the concept of mixing colors in a non-sRGB color space, a first step towards fixing

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Each color code listed is a shorthand for the RGB value. For example, code 609 is equivalent to RGB code 102-0-153 or HEX code #660099

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of text and its background color or at least 3:1 for large text. Enhanced accessibility requires contrast ratios greater than 7:1.

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set, a given transfer curve, adaptive whitepoint, and viewing conditions. These have been chosen to be similar to many real-world

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Extended colors are the result of merging specifications from HTML 4.01, CSS 2.0, SVG 1.0 and CSS3 User Interfaces (CSS3 UI).

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colors. In HTML and XHTML, colors can be used for text, background color, frame borders, tables, and individual table cells.

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the use of system colors in favor of CSS3 UI System Appearance property, which itself was subsequently dropped from CSS3.

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However, addressing accessibility concerns is not simply a matter of increasing the contrast ratio. As a report to the

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palettes selected by various browser applications. There were not very different palettes in use in different browsers.

360:(#). A color is specified according to the intensity of its red, green and blue components, each represented by eight 6436: 5912: 7627: 5352:. They called these 22 colors "the really safe palette"; it consists largely of shades of green, yellow, and cyan. 17: 7852: 7806: 7622: 7611: 304: 4311:

The draft CSS Color 5 specification introduces syntax for mixing and manipulating existing colors, including:

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4.01 specification, ratified in 1999, as follows (names are defined in this context to be case-insensitive):

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Through the 2000s, use of 256-color displays in personal computers dropped sharply in favour of 24-bit (

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