CSS: Setting background opacity without rgba - html

Question

In the following code, I want to set the opacity only for the background color of the li (not the text). However, it is important NOT to use the rgba for the background.
I'm trying following, but it sets the opacity for the link text as well.
HTML:
<ul>
<li>Hello World</li>
</ul>
CSS:
body{
background: red;
}
ul{
margin: 100px;
}
li{
padding: 10px;
background: #000000;
opacity: 0.1;
}
a{
color: #fff;
font-weight: 700;
opacity: 1;
}
JSFiddle:
http://jsfiddle.net/2uJhL/

Answer 1

Old question, but new answer! :)
Fortunately, the new versions of Chrome and Firefox support 8 digit colors. That's really cool, especially when you're developing and testing software.
For example:
background-color: #ff0000; (Red)
If you want a opacity of 0.5, you can do this:
background-color: #ff00007f (The 7F is half of FF)
So, from now on you won't need to use the rgba() if you don't want or have the entire div fade away - because of the opacity: 0.x - when you only want the background color a little bit transparent.
But remember that not all browsers support that. So, please test the snippet below on Chrome or Firefox, ok?
Isn't that cool???
<div style="background-color: #ff00003f;">better than [opacity: 0.25]</div>
<div style="background-color: #ff00007f;">better than [opacity: 0.50]</div>
<div style="background-color: #ff0000bf;">better than [opacity: 0.75]</div>
<div style="background-color: #ff0000ff;">better than [opacity: 1.00]</div>
Source: https://css-tricks.com/8-digit-hex-codes/

Answer 2

You can set a PNG or GIF image as background, i.e:
li {
background-image: url('path/to/your/image.png');
}

Answer 3

The opacity is applied at the content and all children. You can't set a different opacity for the children.
However if you don't want to use rgba you can use a png with opacity that you want.
And setting a png to your li in the background is the best solution in this case

Answer 4

tl;dr Cmiiw, you can't setting the background opacity without RGBA
Let me try to give another solution.
This solution is not the real answer for the problem, but it may helps.
For me, you just need to convert the background color (hex value) to RGBA, using tools something like this https://cssgenerator.org/rgba-and-hex-color-generator.html.
Then, just use the RGBA value in your background color.