A Thing To Know about Gradients and “Transparent Black”

A Thing To Know about Gradients and “Transparent Black”

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Say you have a gradient in CSS that goes from red to transparent. Easy, right? Like this:

.element {
  background: linear-gradient(
    to bottom,
    red, 
    transparent
  );
}

There is a pretty big gotcha here, though.

In Chrome (also Android), Firefox, and Edge, you’d be all good.

But in Safari (also iOS), you’d not be good.

The element on the left in each browser demonstrates the problem.

The problem, the best I understand it, is that transparent is being interpreted (and interpolated) as “transparent black”.

To fix it, you have to set the color as a fully transparent version of that exact color. Like:

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

That’s not always easy with a hex code, since it’s not obvious what the RGBa or HSLa equivalent is. It’s not hard to find a color converter though, just web search around.

The CSS Level 4 color() function will make this easier, Like:

.element {
  background: linear-gradient(
    to bottom,
    #eb8fa9,
    color(#eb8fa9 alpha(0%)) /* or is it color-mod()? */
  )
}

But the support for that isn’t around yet.

Sass can help out, if you are using that:

.element {
  background: linear-gradient(
    to bottom,
    #eb8fa9,
    rgba(#eb8fa9, 0);
  )
}

A Thing To Know about Gradients and “Transparent Black” is a post from CSS-Tricks

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