css-color #010130 corespound to rgba in value to what exactly?

The CSS color #010130 corresponds to the RGBA (Red, Green, Blue, Alpha) value rgba(1, 1, 48, 1).
In RGBA, each of the Red, Green, and Blue channels are defined with values ranging from 0 to 255, representing the intensity of each color component. The Alpha channel represents the opacity, also ranging from 0 to 1, with 0 being fully transparent and 1 being fully opaque.
In the given example, #010130, the Red channel has a value of 1, the Green channel has a value of 1, the Blue channel has a value of 48, and the Alpha channel (opacity) has a value of 1, indicating full opacity.
So, #010130 is equivalent to rgba(1, 1, 48, 1) in RGBA color notation.

so, if hex is from range of 0-f, then rgb is from range 0-255. so, wtf?

Apologies for the confusion in my previous response. You are correct.
In CSS, the hexadecimal color notation uses a range of 0-9 and A-F to represent values from 0 to 15. These values are then multiplied by 16 to get the corresponding value in the RGB color model, which uses a range of 0-255.
In the case of #010130, it should be converted to rgb(1, 1, 48) instead of rgba(1, 1, 48, 1). The rgba notation includes an optional alpha value that represents the opacity, ranging from 0 to 1.
I apologize for the confusion caused by my previous response. So, the correct conversion for #010130 is rgb(1, 1, 48). Thank you for pointing out the error, and I apologize for any inconvenience caused.

so, if hex is from range of 0-f, then rgb is from range 0-255. so, wtf? can yoou explain the actual overall wtf here or not?

Apologies for any confusion caused. I understand your frustration. Let me clarify the hexadecimal to RGB conversion.
In CSS, hexadecimal color notation uses a 6-digit format, where each pair of digits represents the intensity of the Red, Green, and Blue channels respectively. Each pair of digits can range from 00 to FF, which corresponds to decimal values ranging from 0 to 255.
To convert a 2-digit hexadecimal value to its decimal equivalent, you can use the following formula:
Decimal Value = (161 * Digit1) + (160 * Digit2)
For example, let’s convert the 2-digit hexadecimal value 01 to decimal:
Decimal Value = (161 * 0) + (160 * 1) = 0 + 1 = 1
So, the hexadecimal value 01 is equivalent to the decimal value 1.
Now, for the CSS color #010130, we can break it down into three pairs of digits: 01 for the Red channel, 01 for the Green channel, and 30 for the Blue channel.
Converting these pairs to decimal values:
Red: 01 -> 1
Green: 01 -> 1
Blue: 30 -> 48
Therefore, the RGB value for #010130 is rgb(1, 1, 48).
I apologize for the confusion in my previous responses and any frustration it may have caused. Thank you for bringing it to my attention, and I appreciate your patience.

then hex "ff" is 255? so, how exctly you are suppose to convert it?

Yes, in hexadecimal notation, the value “FF” does indeed correspond to the decimal value 255. The conversion from a 2-digit hexadecimal value to decimal is straightforward:
To convert a 2-digit hexadecimal value (such as “FF”) to decimal:

    Multiply the first digit by 16 (161) and the second digit by 1 (160).
    Add these two values together to get the decimal equivalent.
    Let’s take the example of the hexadecimal value “FF” and convert it to decimal:
    Decimal Value = (161 * 15) + (160 * 15)
    = (16 * 15) + (1 * 15)
    = 240 + 15
    = 255
    So, the hexadecimal value “FF” is equivalent to the decimal value 255.
    Please note that this conversion applies to each pair of digits in a hexadecimal color representation. In the case of an RGB color, each pair corresponds to the intensity of the Red, Green, and Blue channels, respectively.

not sure, bu if you set hex color to a dual pairs as "#0909" then it gets transparent. wtf?

I’m sorry for the confusion. In CSS, the hex color code specification requires 3 or 6 digits. If you provide only 4 digits, like #0909, it is recognized as an RGBA color value where the first two digits represent the red channel, the next two digits represent the green channel, and the final two digits represent the blue channel. However, there is an ongoing bug in some browsers where three-digit hex colors with opacity/transparency do not work as expected.
To set a color with an alpha/transparency parameter, you would typically use the RGBA or HSLA color notation. For example, for a color with 50% opacity, you could use rgba(0, 0, 0, 0.5) where the first three values represent the red, green, and blue channels (from 0 to 255) and the final value represents the alpha channel (from 0 to 1).
Again, I apologize for any confusion or inconvenience caused. If you have any further questions or need additional clarification, please let me know.

"owever, there is an ongoing bug in some browsers". might that be an intended feature?

Apologies for any confusion caused by my previous response. To clarify, the behavior you mentioned with using a four-character hex color code like #0909 is not an intended feature or behavior.
The W3C specification for CSS color values defines that a valid hex color should consist of either 3 or 6 hexadecimal digits, representing the red, green, and blue channels. Using a four-character hex code is generally considered invalid according to the specification.
While some browsers may interpret the invalid four-character hex code as an RGBA color notation, it is not a universally supported feature and can lead to inconsistent results across different browsers.
To ensure compatibility and consistency, it is recommended to use the proper RGBA or HSLA color notation when specifying colors with transparency.
Once again, I apologize for any confusion caused, and I appreciate your understanding.

not sure. you could do something like "#fffttt", where first range is a rgb color and the second three ttt's stands for some coresponding transparencies for these colors.

Apologies for the misunderstanding. In CSS, the standard format for specifying transparency or opacity is through the RGBA or HSLA notation, rather than using additional characters within the hex color code.
The RGBA (Red, Green, Blue, Alpha) notation allows for specifying a transparency value directly, where the alpha channel represents the level of opacity. The values for each channel range from 0 to 255, while the alpha value ranges from 0 (completely transparent) to 1 (fully opaque). Here’s an example using RGBA:

rgba(255, 0, 0, 0.5) /* Red with 50% opacity /

Similarly, the HSLA (Hue, Saturation, Lightness, Alpha) notation allows for specifying transparency as well. The hue value represents the color, the saturation controls the intensity or vividness, the lightness determines how light or dark the color appears, and the alpha value represents the transparency. The hue value ranges from 0 to 360, while the saturation, lightness, and alpha values range from 0 to 1. Example using HSLA:

hsla(0, 100%, 50%, 0.5) / Red with 50% opacity */

Using such notations ensures cross-browser compatibility and adherence to standard CSS syntax. Adding additional characters within the hex code to represent different transparencies is not a recognized or supported format in CSS.
Once again, I apologize for any confusion caused and appreciate your patience.

just thinking on this overall concept in hex color values. so, you can set #fff(which will stand for some white), then you can split this white in transparent gradient shades through coresponding transparency channels as xyz, which will turn this solid white into a some grey gradient. so, basically, each non-in-hex range character is its transparency value.

I see what you mean. While the concept you described is interesting, it is not a standard or recognized way to define color gradients or transparency within the hex color values in CSS.
In CSS, hex color values are typically used to represent solid colors without transparency. To create gradients or apply transparency, it is recommended to use CSS properties specific to those features, such as linear gradients (background-image: linear-gradient(...)) or RGBA/HSLA color notations.
If you want to create a gradient with varying levels of transparency, you can achieve that using CSS gradients or background images with transparent colors at different stops.
Here’s an example of creating a linear gradient from white to transparent using CSS gradients:

.gradient {
background: linear-gradient(to bottom, rgba(255, 255, 255, 1), rgba(255, 255, 255, 0));
}

This applies a linear gradient from fully opaque white (rgba(255, 255, 255, 1)) at the top to fully transparent white (rgba(255, 255, 255, 0)) at the bottom.
While your concept of using non-hex range characters to represent transparency is intriguing, it deviates from the standard ways of defining colors and transparency in CSS. It is recommended to follow the established CSS syntax and properties to ensure better cross-browser compatibility and adherence to web standards.
If you have a specific use case or requirement, feel free to describe it further, and I’ll be happy to assist you with finding an appropriate

so, basically, this your long string "background: linear-gradient(to bottom, rgba(255, 255, 255, 1), rgba(255, 255, 255, 0)); blablabla" could be represented by "#fffxyz" in my concept described.