https://www.w3schools.com/css/css_colors_hex.asp
A hexadecimal color is specified with: #RRGGBB, where the RR (red), GG (green) and BB (blue) hexadecimal integers specify the components of the color.
HEX Value
In CSS, a color can be specified using a hexadecimal value in the form:
#rrggbb
Where rr (red), gg (green) and bb (blue) are hexadecimal values between 00 and ff (same as decimal 0-255).
For example, #ff0000 is displayed as red, because red is set to its highest value (ff) and the others are set to the lowest value (00).
To display black, set all values to 00, like this: #000000.
To display white, set all values to ff, like this: #ffffff.
Experiment by mixing the HEX values below:
<!DOCTYPE html> <html> <body> <h1>Specify colors using HEX values</h1> <h2 style="background-color:#ff0000;">#ff0000</h2> <h2 style="background-color:#0000ff;">#0000ff</h2> <h2 style="background-color:#3cb371;">#3cb371</h2> <h2 style="background-color:#ee82ee;">#ee82ee</h2> <h2 style="background-color:#ffa500;">#ffa500</h2> <h2 style="background-color:#6a5acd;">#6a5acd</h2> </body> </html>
Shades of gray are often defined using equal values for all the 3 light sources:
<!DOCTYPE html> <html> <body> <h1>Shades of gray</h1> <p>By using equal values for red, green, and blue, you will get different shades of gray:</p> <h2 style="background-color:#3c3c3c;">#3c3c3c</h2> <h2 style="background-color:#616161;">#616161</h2> <h2 style="background-color:#787878;">#787878</h2> <h2 style="background-color:#b4b4b4;">#b4b4b4</h2> <h2 style="background-color:#f0f0f0;">#f0f0f0</h2> <h2 style="background-color:#f9f9f9;">#f9f9f9</h2> </body> </html>
3 Digit HEX Value
Sometimes you will see a 3-digit hex code in the CSS source.
The 3-digit hex code is a shorthand for some 6-digit hex codes.
The 3-digit hex code has the following form:
#rgb
Where r, g, and b represent the red, green, and blue components with values between 0 and f.
The 3-digit hex code can only be used when both the values (RR, GG, and BB) are the same for each component. So, if we have #ff00cc, it can be written like this: #f0c.
Here is an example:
Example
body {background-color: #fc9; /* same as #ffcc99 */
}
h1 {
color: #f0f; /* same as #ff00ff */
}
p {
color: #b58; /* same as #bb5588 */
}
<!DOCTYPE html>
<html>
<head>
<style>
body {
background-color: #fc9; /* same as #ffcc99 */
}
h1 {
color: #f0f; /* same as #ff00ff */
}
p {
color: #b58; /* same as #bb5588 */
}
</style>
</head>
<body>
<h1>CSS 3-digit Hex Code</h1>
<p>This is a paragraph.</p>
</body>
</html>
标签：digit,css12,color,hex,HEX,same,Colors,values,red From： https://www.cnblogs.com/emanlee/p/18221257