<alpha-value>
CSS
data type
represents a value that can be either a
<number>
或
<percentage>
, specifying the
alpha channel
or
transparency
of a color.
The value of an
<alpha-value>
is given as either a
<number>
或
<percentage>
.
If given as a number, the useful range is 0 (fully transparent) to 1.0 (fully opaque), with decimal values in between; that is, 0.5 indicates that half of the foreground color is used and half of the background color is used. Values outside the range of 0 to 1 are permitted, but are clamped to like within the range 0 to 1.
If the alpha value is given as a percentage, 0% corresponds to fully transparent while 100% indicates fully opaque.
When animated, values of the
<alpha-value>
CSS data type are interpolated as real, floating-point numbers. The speed of the interpolation is determined by the
timing function
associated with the animation.
Here an alpha value is used to set partially transparent text:
/* <rgba()> */ color: rgba(34, 12, 64, 0.6); color: rgba(34.0 12 64 / 60%);
Here an alpha value is used to determine which parts of an image are considered part of a shape:
/* shape-image-threshold */ shape-image-threshold: 70%; shape-image-threshold: 0.7;
| 规范 | 状态 | 注释 |
|---|---|---|
|
CSS Color Module Level 4
The definition of '<alpha-value>' in that specification. |
工作草案 | No significant change. |
|
CSS Color Module Level 3
The definition of '<alpha-value>' in that specification. |
推荐 |
Introduces
<alpha-value>
along with
rgba()
and
hsla()
functional notations.
|
