CSS Color Names + Alpha Transparency

CSS color names + alpha transparency

You can achieve the result you want this way:

#mytext{
  color: red;
  opacity: 0.5;
}

Note that opacity will affect the whole element, not just the text, so for example, if the #mytext element had a background color, that would also receive the opacity value of 0.5

However, I agree with Dai, using color names instead of hex or rgb codes isn't something you should rely on too much. It's an ugly color palette to work with.

Set CSS color using color text name like red and also set opacity?

As far as the MDN documentation on this tells us, you should be using rgba(r,g,b,a) or even hsla(h,s,l,a) if you want to pick a color with alpha. So it is not possible to do what you were trying to achieve using the first way you showed.

Is there a color code for transparent in HTML?

There is not a Transparent color code, but there is an Opacity styling. Check out the documentation about it over at developer.mozilla.org

You will probably want to set the color of the element and then apply the opacity to it.

.transparent-style{

    background-color: #ffffff;
    opacity: .4;

}

You can use some online transparancy generatory which will also give you browser specific stylings. e.g. take a look at http://www.css-opacity.pascal-seven.de/

Note though that when you set the transparency of an element, any child element becomes transparent also. So you really need to overlay any other elements.

You may also want to try using an RGBA colour using the Alpha (A) setting to change the opacity. e.g.

.transparent-style{
    background-color: rgba(255, 255, 255, .4);
}

Using RGBA over opacity means that your child elements are not transparent.

Add alpha channel to a given color

I believe there is no way to do it.

Css is very limited by itself, and there isn't much you can do with it.

The only way you could add opacity is:

opacity: 0.5

But the above would also affect the text itself, not only background.

However, you could wrap it in way that would separate the background blocks from the text, so that would keep the color of the text untouched.

EDIT: See the fiddle: http://jsfiddle.net/YfSn7/30/

But that may look somewhat ridiculous, so I wouldn't much advice using it.

Guess you would have to accept that this is impossible, if you do actually want to make things simpler instead of over-complicating them.

What is the color code for transparency in CSS?

how to make transparent elements with css:

CSS for IE:

filter: alpha(opacity = 52);

CSS for other browsers:

opacity:0.52;

How do I apply opacity to a CSS color variable?

You can't take an existing color value and apply an alpha channel to it. Namely, you can't take an existing hex value such as #f0f0f0, give it an alpha component and use the resulting value with another property.

However, custom properties allow you to convert your hex value into an RGB triplet for use with rgba(), store that value in the custom property (including the commas!), substitute that value using var() into an rgba() function with your desired alpha value, and it'll just work:

:root {
  /* #f0f0f0 in decimal RGB */
  --color: 240, 240, 240;
}

body {
  color: #000;
  background-color: #000;
}

#element {
  background-color: rgba(var(--color), 0.8);
}

<p id="element">If you can see this, your browser supports custom properties.</p>

Finding equivalent color with opacity

Color blending is just a linear interpolation per channel, right? So the math is pretty simple. If you have RGBA1 over RGB2, the effective visual result RGB3 will be:

r3 = r2 + (r1-r2)*a1
g3 = g2 + (g1-g2)*a1
b3 = b2 + (b1-b2)*a1

…where the alpha channel is from 0.0 to 1.0.

Sanity check: if the alpha is 0, is RGB3 the same as RGB2? Yes. If the alpha is 1, is RGB3 the same as RGB1? Yes.

If you locked down only the background color and final color, there are a large number of RGBA colors (infinite, in floating-point space) that could satisfy the requirements. So you have to pick either the color of the bar or the opacity level you want, and find out the value of the other.

Picking the Color Based on Alpha

If you know RGB3 (the final desired color), RGB2 (the background color), and A1 (how much opacity you want), and you are just looking for RGB1, then we can re-arrange the equations thusly:

r1 = (r3 - r2 + r2*a1)/a1
g1 = (g3 - g2 + g2*a1)/a1
b1 = (b3 - b2 + b2*a1)/a1

There are some color combinations which are theoretically possible, but impossible given the standard RGBA range. For example, if the background is pure black, the desired perceived color is pure white, and the desired alpha is 1%, then you would need:

r1 = g1 = b1 = 255/0.01 = 25500

…a super-bright white 100× brighter than any available.

Picking the Alpha Based on Colors

If you know RGB3 (the final desired color), RGB2 (the background color), and RGB1 (the color you have that you want to vary the opacity of), and you are just looking for A1, then we can re-arrange the equations thusly:

a1 = (r3-r2) / (r1-r2)
a1 = (g3-g2) / (g1-g2)
a1 = (b3-b2) / (b1-b2)

If these give different values, then you can't make it match exactly, but you can average the alphas to get as close as possible. For example, there's no opacity in the world that will let you put green over red to get blue.

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