Temani Afif

Posted on Feb 12, 2021 • Edited on Nov 12

Border with gradient and radius

#css #webdev #html

^{Find out more CSS tricks at css-tip.com}

We all know the property border-image that allows us to add any kind of images (including gradients) as borders.

.box {
  border: 10px solid;
  border-image: linear-gradient(45deg,red,blue) 10;
}

Unfortunately, border-radius isn't supported with border-image and it's painful to find tricks to obtain rounded borders having a gradient.

Here is a trick that will produce such a result. No complex code, No SVG, or multiple elements are required! only two lines of CSS code using the mask property.

.box {
  border-radius: 50px; /*1*/
  border: 10px solid transparent; /*2*/
  background: linear-gradient(45deg,red,blue) border-box; /*3*/
  mask: /*4*/
    linear-gradient(#000 0 0) padding-box, 
    linear-gradient(#000 0 0);
  mask-composite: exclude; /*5*/
}

Explanation

(1)(2): Those lines are trivial.
(3): We apply a gradient as background and we make its origin the border box (by default it's the padding box).
(4): Using the mask property, we apply two opaque layers. The bottom one will cover the whole element and the top one will cover only the padding box (so it will not cover the border area)
(5): We exclude the top layer from the bottom one so that only the border area will be shown!

That's it!

Now you can adjust the border, gradient, and radius as you want. The only drawback is that this will mask the content so we can move the code to a pseudo-element instead

.box {
  position: relative;
}
.box::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 50px; 
  padding: 10px; 
  background:linear-gradient(45deg,red,blue); 
  mask: 
    linear-gradient(#000 0 0) content-box, 
    linear-gradient(#000 0 0);
  mask-composite: exclude; 
}

I replaced the border with padding to make the code shorter but the logic remains the same: we exclude the content area from the padding area so only padding will remain visible

OR

Top comments (32)

Veri • May 30

Thanks

David Hyland • Aug 16

This helped enormously, thank you!

eshimischi • Feb 19 '22

But what if i need to make a background colour as well? for instance, gradient as well

Temani Afif • Feb 19 '22

in this case, you don't need mask or pseudo element simply do

.box {
  border:8px solid #0000;
  border-radius:10px;
  background:
    linear-gradient(red,blue) padding-box,
    linear-gradient(green,pink) border-box;
}

Mads Stoumann • Mar 2 '22

This is SO much cleaner than all the "gradient border"-articles you find around the web — love the 4-char alpha-hex. Thank You!

eshimischi • Feb 19 '22 • Edited

Well i tried what you said, but it looks very much differently from what i want to archive and it's so sad.

PS: i decided simply to export the background with border as a background (svg), the simplest way

eshimischi • Feb 19 '22 • Edited

thanks for the tip, will try.. my designer made this, at first i tried it with a border-image-source but it doesn't work with border-radius, of course

nat_souljah • Sep 28 '22

Thus just saved me more digging, thanks muchacho

Nate Dolesh • Aug 9 '21

Thanks, it could work in some situations, although two issues:

I had to add z-index: -1; to the ::before pseudo element to make the content clickable/selectable
After doing the above, the border won't be visible if any parent element has a background

Temani Afif • Aug 9 '21

if you are adding z-index:-1 to the pseudo element you need to add z-index:0 to the main element to avoid the issue OR don't use z-index at all and add pointer-events:none to the pseudo element