View source for CSS3/Color/RGBA

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* [[CSS3/Color|Color]]
** [[CSS3/Color#.3Ccolor.3E_Values|<color> Values]]
***[[CSS3/Color/Basic_color_keywords|Basic color keywords]]
***[[CSS3/Color/RGB|RGB]]
***[[CSS3/Color/RGBA|RGBA]]
***[[CSS3/Color/transparent|transparent]]
***[[CSS3/Color/HSL|HSL]]
***[[CSS3/Color/HSLA|HSLA]]
***[[CSS3/Color/Extended_color_keywords|Extended color keywords]]
***[[CSS3/Color/currentColor|currentColor]]

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= RGBA(Red-Green-Blue-Alpha) =
The RGB color model is extended in this specification to include “alpha” to allow specification of the opacity of a color.

== The format of the RGBA Value ==
*<code>rgba(R,G,B,A) -integer-</code><br />The format of an RGBA value in the functional notation is ‘rgba(’ followed by a comma-separated list of three numerical values (three integer values), followed by an [[CSS3/Color/opacity#alphavalue|<alphavalue>]], followed by ‘)’.


*<code>rgba(R,G,B,A) -percentage-</code><br />The format of an RGBA value in the functional notation is ‘rgba(’ followed by a comma-separated list of three numerical values (three percentage values), followed by an [[CSS3/Color/opacity#alphavalue|<alphavalue>]], followed by ‘)’.


== Example ==
<table class="filehistory" style="line-height: 1.5em;">
  <tr>
    <th>Alpha</th><th>hsla(H,S,L,A)</th><th>Color</th><th>&nbsp;</th>
  </tr>
  <tr>
    <td>0.0</td><td>rgba(255, 0, 0, 0.0)</td><td style="background-color: rgba(255, 0, 0, 0.0);">&nbsp;</td><td>fully transparent</td>
  </tr>
  <tr>
    <td>0.2</td><td>rgba(255, 0, 0, 0.2)</td><td style="background-color: rgba(255, 0, 0, 0.2);">&nbsp;</td><td>&nbsp;</td>
  </tr>
  <tr>
    <td>0.4</td><td>rgba(255, 0, 0, 0.4)</td><td style="background-color: rgba(255, 0, 0, 0.4);">&nbsp;</td><td>&nbsp;</td>
  </tr>
  <tr>
    <td>0.6</td><td>rgba(255, 0, 0, 0.6)</td><td style="background-color: rgba(255, 0, 0, 0.6);">&nbsp;</td><td>&nbsp;</td>
  </tr>
  <tr>
    <td>0.8</td><td>rgba(255, 0, 0, 0.8)</td><td style="background-color: rgba(255, 0, 0, 0.8);">&nbsp;</td><td>&nbsp;</td>
  </tr>
  <tr>
    <td>1.0</td><td>rgba(255, 0, 0, 1.0)</td><td style="background-color: rgba(255, 0, 0, 1.0);">&nbsp;</td><td>fully opaque</td>
  </tr>
</table>


== Point, Note ==
*If RGBA values are not supported by a user agent, they should be treated like unrecognized values per the CSS forward compatibility parsing rules ([CSS21], Chapter 4). RGBA values must not be treated as simply an RGB value with the opacity ignored. 


== CSS Reference ==
The CSS Color Module Level 3 specification defines the RGBA color values in [http://www.w3.org/TR/css3-color/#rgba-color 4.2.2. RGBA color values].