HTML颜色 HTML colors
HTML colors are specified using predefined color names, or RGB, HEX, HSL, RGBA, HSLA values.
详细的颜色设置和数值，参见https://www.w3schools.com/colors/default.asp
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Color names
HTML supports 140 standard color names.
Background color
Hello World
Lorem ipsum...
Text color
Hello World
Lorem ipsum...
Ut wisi enim...
Border color
Hello World
Hello World
Hello World
RGB
rgb(red红, green绿, blue蓝)
Each parameter (red, green, and blue) defines the intensity of the color between 0 and 255.
For example, rgb(255, 0, 0) is displayed as red, because red is set to its highest value (255) and the others are set to 0.
To display the color black, all color parameters must be set to 0, like this: rgb(0, 0, 0).
To display the color white, all color parameters must be set to 255, like this: rgb(255, 255, 255).
HEX
In HTML, 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).
HSL
In HTML, a color can be specified using hue, saturation, and lightness (HSL) in the form:
hsl(hue色度, saturation饱和度, lightness亮度)
Hue is a degree on the color wheel from 0 to 360. 0 is red, 120 is green, and 240 is blue.
Saturation is a percentage value, 0% means a shade of gray, and 100% is the full color.
Saturation can be described as the intensity of a color. 100% is pure color, no shades of gray. 50% is 50% gray, but you can still see the color. 0% is completely gray, you can no longer see the color.
Lightness is also a percentage, 0% is black, 50% is neither light or dark, 100% is white
The lightness of a color can be described as how much light you want to give the color, where 0% means no light (black), 50% means 50% light (neither dark nor light) 100% means full lightness (white).
Shades of gray are often defined by setting the hue and saturation to 0, and adjust the lightness from 0% to 100% to get darker/lighter shades.
RGBA
RGBA color values are an extension of RGB color values with an alpha channel - which specifies the opacity for a color.
An RGBA color value is specified with:
rgba(red, green, blue, alpha)
The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (not transparent at all).
HSLA
HSLA color values are an extension of HSL color values with an alpha channel - which specifies the opacity for a color.
An HSLA color value is specified with:
hsla(hue, saturation, lightness, alpha)
The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (not transparent at all).
HTML颜色页面参见：
https://www.w3schools.com/html/html_colors.asp