Color definition in CSS

This information came from the W3C Specifications.

General Color

Colors can be specified by any of the following methods:

Transparency is specified by:

color: rgba(0, 0, 0, 0.5) /* 50% opacity */

To make a background fully transparent, you could use the "transparent" value. Ex:

.clearBkgd {
	background-color: transparent;
}

Opacity

This is yet another method for making color and background color semi-transparent, but it can also be applied to DOM elements.

DOM elements (such as <div>, <p>, <h1>, <img>, etc.) can be given transparency by using the opacity property. Everything about that element (background, images, text...) will inherit the specified opacity. Ex:

.seventyPercent {
	opacity:0.7; /* for Webkit, Gecko, IE9+ */
	filter: alpha(opacity=70); /* for IE8 and earlier */
}

Color

The color name is not case-sensitive. "antiquewhite" = "AntiqueWhite"

Sort colors by Lightness or Hue.

Named Numeric Color name Hex rgb Decimal
    aliceblue #f0f8ff 240,248,255
    antiquewhite #faebd7 250,235,215
    aqua #00ffff 0,255,255
    aquamarine #7fffd4 127,255,212
    azure #f0ffff 240,255,255
    beige #f5f5dc 245,245,220
    bisque #ffe4c4 255,228,196
    black #000000 0,0,0
    blanchedalmond #ffebcd 255,235,205
    blue #0000ff 0,0,255
    blueviolet #8a2be2 138,43,226
    brown #a52a2a 165,42,42
    burlywood #deb887 222,184,135
    cadetblue #5f9ea0 95,158,160
    chartreuse #7fff00 127,255,0
    chocolate #d2691e 210,105,30
    coral #ff7f50 255,127,80
    cornflowerblue #6495ed 100,149,237
    cornsilk #fff8dc 255,248,220
    crimson #dc143c 220,20,60
    cyan #00ffff 0,255,255
    darkblue #00008b 0,0,139
    darkcyan #008b8b 0,139,139
    darkgoldenrod #b8860b 184,134,11
    darkgray #a9a9a9 169,169,169
    darkgreen #006400 0,100,0
    darkkhaki #bdb76b 189,183,107
    darkmagenta #8b008b 139,0,139
    darkolivegreen #556b2f 85,107,47
    darkorange #ff8c00 255,140,0
    darkorchid #9932cc 153,50,204
    darkred #8b0000 139,0,0
    darksalmon #e9967a 233,150,122
    darkseagreen #8fbc8f 143,188,143
    darkslateblue #483d8b 72,61,139
    darkslategray #2f4f4f 47,79,79
    darkturquoise #00ced1 0,206,209
    darkviolet #9400d3 148,0,211
    deeppink #ff1493 255,20,147
    deepskyblue #00bfff 0,191,255
    dimgray #696969 105,105,105
    dodgerblue #1e90ff 30,144,255
    firebrick #b22222 178,34,34
    floralwhite #fffaf0 255,250,240
    forestgreen #228b22 34,139,34
    fuchsia #ff00ff 255,0,255
    gainsboro #dcdcdc 220,220,220
    ghostwhite #f8f8ff 248,248,255
    gold #ffd700 255,215,0
    goldenrod #daa520 218,165,32
    gray #808080 128,128,128
    green #008000 0,128,0
    greenyellow #adff2f 173,255,47
    honeydew #f0fff0 240,255,240
    hotpink #ff69b4 255,105,180
    indianred #cd5c5c 205,92,92
    indigo #4b0082 75,0,130
    ivory #fffff0 255,255,240
    khaki #f0e68c 240,230,140
    lavender #e6e6fa 230,230,250
    lavenderblush #fff0f5 255,240,245
    lawngreen #7cfc00 124,252,0
    lemonchiffon #fffacd 255,250,205
    lightblue #add8e6 173,216,230
    lightcoral #f08080 240,128,128
    lightcyan #e0ffff 224,255,255
    lightgoldenrodyellow #fafad2 250,250,210
    lightgray #d3d3d3 211,211,211
    lightgreen #90ee90 144,238,144
    lightpink #ffb6c1 255,182,193
    lightsalmon #ffa07a 255,160,122
    lightseagreen #20b2aa 32,178,170
    lightskyblue #87cefa 135,206,250
    lightslategray #778899 119,136,153
    lightsteelblue #b0c4de 176,196,222
    lightyellow #ffffe0 255,255,224
    lime #00ff00 0,255,0
    limegreen #32cd32 50,205,50
    linen #faf0e6 250,240,230
    magenta #ff00ff 255,0,255
    maroon #800000 128,0,0
    mediumaquamarine #66cdaa 102,205,170
    mediumblue #0000cd 0,0,205
    mediumorchid #ba55d3 186,85,211
    mediumpurple #9370db 147,112,219
    mediumseagreen #3cb371 60,179,113
    mediumslateblue #7b68ee 123,104,238
    mediumspringgreen #00fa9a 0,250,154
    mediumturquoise #48d1cc 72,209,204
    mediumvioletred #c71585 199,21,133
    midnightblue #191970 25,25,112
    mintcream #f5fffa 245,255,250
    mistyrose #ffe4e1 255,228,225
    moccasin #ffe4b5 255,228,181
    navajowhite #ffdead 255,222,173
    navy #000080 0,0,128
    oldlace #fdf5e6 253,245,230
    olive #808000 128,128,0
    olivedrab #6b8e23 107,142,35
    orange #ffa500 255,165,0
    orangered #ff4500 255,69,0
    orchid #da70d6 218,112,214
    palegoldenrod #eee8aa 238,232,170
    palegreen #98fb98 152,251,152
    paleturquoise #afeeee 175,238,238
    palevioletred #db7093 219,112,147
    papayawhip #ffefd5 255,239,213
    peachpuff #ffdab9 255,218,185
    peru #cd853f 205,133,63
    pink #ffc0cb 255,192,203
    plum #dda0dd 221,160,221
    powderblue #b0e0e6 176,224,230
    purple #800080 128,0,128
    red #ff0000 255,0,0
    rosybrown #bc8f8f 188,143,143
    royalblue #4169e1 65,105,225
    saddlebrown #8b4513 139,69,19
    salmon #fa8072 250,128,114
    sandybrown #f4a460 244,164,96
    seagreen #2e8b57 46,139,87
    seashell #fff5ee 255,245,238
    sienna #a0522d 160,82,45
    silver #c0c0c0 192,192,192
    skyblue #87ceeb 135,206,235
    slateblue #6a5acd 106,90,205
    slategray #708090 112,128,144
    snow #fffafa 255,250,250
    springgreen #00ff7f 0,255,127
    steelblue #4682b4 70,130,180
    tan #d2b48c 210,180,140
    teal #008080 0,128,128
    thistle #d8bfd8 216,191,216
    tomato #ff6347 255,99,71
    turquoise #40e0d0 64,224,208
    violet #ee82ee 238,130,238
    wheat #f5deb3 245,222,179
    white #ffffff 255,255,255
    whitesmoke #f5f5f5 245,245,245
    yellow #ffff00 255,255,0
    yellowgreen #9acd32 154,205,50

Algorithm for converting between RGB and HSB