Introduction to CSS Colors

We’ll cover all the available methods for specifying colors with CSS in this guide.

There are six ways to declare CSS colors:

  • Hexadecimal notation
  • RGB
  • RGBA
  • HSL
  • HSLA
  • Color keywords

Hexadecimal

Example

div {
 background-color: #000000;
}

Result

 

Hexadecimal color notation is a way of declaring a color by indicating the amount of red, green and blue (RGB) it has.

This color notation is based on the hexadecimal numeral system (base 16).

We’re more accustomed to the decimal numeral system (base 10), so hex is a bit tricky to understand at first.

In the example above, black was declared as #000000, which means it has no red, green or blue. (Color theory tells us that the absence of any color is black.)

In CSS hex color notation:

  • The amount of red is specified by the first two characters
  • The amount of green is specified by the second two characters
  • The amount of blue is specified by the last two characters

How to read hex color notation

A valid CSS hex color starts with a hash (#) followed by either six characters or three characters. Characters can be between 0-9 and A-F (or lowercase a-f).

The minimum value of each color channel is 00, which is equal to 0 in the decimal numeral system.

The maximum value of each color channel is FF, which is equal to 255 in the decimal numeral system.

So, knowing all of that, if we specify black, then:

Red Green Blue Hex color notation
00 (0 in decimal) 00 (0 in decimal) 00 (0 in decimal) #000000

What if we wanted blue?

We can set the amount of blue to the maximum value (i.e. FF):

Red Green Blue Hex color notation
00 (0 in decimal) 00 (0 in decimal) FF (255 in decimal) #0000FF

Result

 

We can specify a vast amount of colors simply by adjusting the amount of red, green and blue in the color.

Let’s say we wanted get the color purple. We can do this by mixing together a bit of red with a bit of blue, and by leaving out any green.

Red Green Blue Hex color notation
80 (128 in decimal) 00 (0 in decimal) 80 (128 in decimal) #800080

Result

 

In hex color notation, two consecutive characters that are identical can be shortened to just one character. That’s why CSS hex color notation can also be written with just 3 characters.

For example:

  • #FF00FF is the same as #F0F
  • #DDCC11 is the same as #DC1
  • #000000 is the same as #000
  • #FFFFFF is the same as #FFF

For alphabetic characters, you can use lowercases.

For example:

  • #FFFFFF is the same as #ffffff
  • #C0C0C0 is the same as #c0c0c0
  • #ABCDEF is the same as #abcdef

RGB

Example

div {
 background-color: rgb(0, 0, 0);
}

Result

 

The decimal numeral system is what we’re most used to. It’s usually the system we’re taught in school, and it’s how most numbers are displayed in our world.

The hexadecimal numeral system, on the other hand, isn’t mainstream; it isn’t used much outside computer programming and math-related fields.

RGB color notation is a more intuitive way of declaring CSS colors because it uses the decimal numeral system.

The syntax format is:

rgb(red, green, blue)

OK, so we already know that:

  • 0 is the minimum decimal value
  • 255 is the maximum decimal value

Blue can be specified as:

Red Green Blue RGB color notation
0 0 255 rgb(0, 0, 255)

Result

 

RGBA

Example

div {
 color: rgba(255, 255, 255, 0.20);
 background: url(bg.jpg) no-repeat center center;
}

Result

Sample Text

RGBA is just an extension of RGB, with an added alpha (A) parameter that specifies the level of transparency/opacity the color has. Thus, we can use RGBA color values to make HTML elements semi-transparent.

Alpha can be a value between 0 and 1.

The basic format of RGBA is:

rgba(red, green, blue, alpha)

If we want blue with 25% opacity:

Red Green Blue Opacity RGBA color notation
0 0 255 0.25 rgba(0, 0, 255, 0.25)

For an in-depth discussion of RGBA, read this: A Guide to CSS RGBA Colors.

HSL

Example

div {
 background-color: hsl(240, 100%, 50%);
}

Result

 

HSL stands for Hue, Saturation and Lightness.

The HSL color notation is an alternative to the RGB color notation. It was introduced to CSS with the idea that it’s more intuitive to learn compared to the RGB color system.

The basic syntax is:

hsl(hue, saturation, lightness)

Hue refers to the colors we can see. The range of colors visible to the human eye can be charted in a circle, often referred to as the color wheel. Therefore, hue can be a value between 0 and 360.

source

Looking at the color wheel above, we can see that red is at 0o, green is at 90o, purple is at 270o, and so forth.

Saturation refers to the vividness or "colorfulness" of the hue. A low saturation value leads to a muted hue, while a high saturation value leads to a brighter hue. Saturation can be between 0% and 100%.

Lightness refers to how light or dark the hue is. The higher the value, the lighter the color is. Lightness can also be a value between 0% and 100%.

It’s easy to look at saturation and lightness as the fine-tuning of the hue.

Let’s say we want a pure red. Looking at the color wheel again, red is at 0o. So to get pure red, we can set the saturation to 100% to get the maximum amount of red color, and lightness to 50%.

Hue Saturation Lightness HSL color notation
0 100% 50% hsl(0, 100%, 50%)

Result

 

If we wanted to have a muted/dull red, we can still use the same hue. We just need to lower the saturation to reduce the color’s vividness.

Hue Saturation Lightness HSL color notation
0 50% 50% hsl(0, 50%, 50%)

Result

 

If we want a dark red, we can lower the lightness value.

Hue Saturation Lightness HSL color notation
0 100% 25% hsl(0, 100%, 25%)

Result

 

HSLA

Example

div {
 color: hsla(120, 100%, 50%, 0.2);
 background: url(bg.jpg) no-repeat center center;
}

Result

Sample Text

HSLA is just like HSL with an added Alpha (A) parameter that allows us to specify the level of transparency/opacity of the color.

The basic syntax is:

hsla(hue, saturation, lightness, alpha)

Alpha can be a value between 0 and 1.

Color Keywords

Example

div {
 background-color: fuchsia;
}

Result

 

Basic Color Names

CSS has 16 basic color names. Examples of basic color names are blue, maroon, black and white.

Basic Color Names Chart

Color Color Name Hex
  black #000000
  silver #C0C0C0
  gray #808080
  white #FFFFFF
  maroon #800000
  red #FF0000
  purple #800080
  fuchsia #FF00FF
  green #008000
  lime #00FF00
  olive #808000
  yellow #FFFF00
  navy #000080
  blue #0000FF
  teal #008080
  aqua #00FFFF

source

Extended Color Names

CSS2 and CSS3 introduced a lot more color names. Examples of extended color names are thistle, crimson and saddlebrown.

Example

div {
 background-color: olivedrab;
}

Result

 

Extended Color Names Chart

Color Color Name Hex
  aliceblue #F0F8FF
  antiquewhite #FAEBD7
  aqua #00FFFF
  aquamarine #7FFFD4
  azure #F0FFFF
  beige #F5F5DC
  bisque #FFE4C4
  black #000000
  blanchedalmond #FFEBCD
  blue #0000FF
  blueviolet #8A2BE2
  brown #A52A2A
  burlywood #DEB887
  cadetblue #5F9EA0
  chartreuse #7FFF00
  chocolate #D2691E
  coral #FF7F50
  cornflowerblue #6495ED
  cornsilk #FFF8DC
  crimson #DC143C
  cyan #00FFFF
  darkblue #00008B
  darkcyan #008B8B
  darkgoldenrod #B8860B
  darkgray #A9A9A9
  darkgreen #006400
  darkgrey #A9A9A9
  darkkhaki #BDB76B
  darkmagenta #8B008B
  darkolivegreen #556B2F
  darkorange #FF8C00
  darkorchid #9932CC
  darkred #8B0000
  darksalmon #E9967A
  darkseagreen #8FBC8F
  darkslateblue #483D8B
  darkslategray #2F4F4F
  darkslategrey #2F4F4F
  darkturquoise #00CED1
  darkviolet #9400D3
  deeppink #FF1493
  deepskyblue #00BFFF
  dimgray #696969
  dimgrey #696969
  dodgerblue #1E90FF
  firebrick #B22222
  floralwhite #FFFAF0
  forestgreen #228B22
  fuchsia #FF00FF
  gainsboro #DCDCDC
  ghostwhite #F8F8FF
  gold #FFD700
  goldenrod #DAA520
  gray #808080
  green #008000
  greenyellow #ADFF2F
  grey #808080
  honeydew #F0FFF0
  hotpink #FF69B4
  indianred #CD5C5C
  indigo #4B0082
  ivory #FFFFF0
  khaki #F0E68C
  lavender #E6E6FA
  lavenderblush #FFF0F5
  lawngreen #7CFC00
  lemonchiffon #FFFACD
  lightblue #ADD8E6
  lightcoral #F08080
  lightcyan #E0FFFF
  lightgoldenrodyellow #FAFAD2
  lightgray #D3D3D3
  lightgreen #90EE90
  lightgrey #D3D3D3
  lightpink #FFB6C1
  lightsalmon #FFA07A
  lightseagreen #20B2AA
  lightskyblue #87CEFA
  lightslategray #778899
  lightslategrey #778899
  lightsteelblue #B0C4DE
  lightyellow #FFFFE0
  lime #00FF00
  limegreen #32CD32
  linen #FAF0E6
  magenta #FF00FF
  maroon #800000
  mediumaquamarine #66CDAA
  mediumblue #0000CD
  mediumorchid #BA55D3
  mediumpurple #9370DB
  mediumseagreen #3CB371
  mediumslateblue #7B68EE
  mediumspringgreen #00FA9A
  mediumturquoise #48D1CC
  mediumvioletred #C71585
  midnightblue #191970
  mintcream #F5FFFA
  mistyrose #FFE4E1
  moccasin #FFE4B5
  navajowhite #FFDEAD
  navy #000080
  oldlace #FDF5E6
  olive #808000
  olivedrab #6B8E23
  orange #FFA500
  orangered #FF4500
  orchid #DA70D6
  palegoldenrod #EEE8AA
  palegreen #98FB98
  paleturquoise #AFEEEE
  palevioletred #DB7093
  papayawhip #FFEFD5
  peachpuff #FFDAB9
  peru #CD853F
  pink #FFC0CB
  plum #DDA0DD
  powderblue #B0E0E6
  purple #800080
  red #FF0000
  rosybrown #BC8F8F
  royalblue #4169E1
  saddlebrown #8B4513
  salmon #FA8072
  sandybrown #F4A460
  seagreen #2E8B57
  seashell #FFF5EE
  sienna #A0522D
  silver #C0C0C0
  skyblue #87CEEB
  slateblue #6A5ACD
  slategray #708090
  slategrey #708090
  snow #FFFAFA
  springgreen #00FF7F
  steelblue #4682B4
  tan #D2B48C
  teal #008080
  thistle #D8BFD8
  tomato #FF6347
  turquoise #40E0D0
  violet #EE82EE
  wheat #F5DEB3
  white #FFFFFF
  whitesmoke #F5F5F5
  yellow #FFFF00
  yellowgreen #9ACD32

source

transparent Color Keyword

The transparent color keyword is simply a way to say that the color has 0% opacity.

Example

div {
 background-color: transparent;
}

currentColor Color Keyword

The currentColor color keyword is a convenience keyword that just means the color being declared is equal to the CSS color property value:

For example:

div {
 color: blue;
 border: 1px solid blue;
 box-shadow: 2px 2px 15px blue;
 background: blue;
}

Can also be written as:

div {
 color: blue;
 border: 1px solid currentColor;
 box-shadow: 2px 2px 15px currentColor;
 background: currentColor;
}

Result

 

The benefit of using the currentColor color keyword is that if you need to update a rule-set, you only need to update the color property value.

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