Creating a triangle in css with a gradient background

Question

I am trying to create a triangle in css with a gradient background. I have not had any success as yet. Is there way to do this to bring off this effect seen in the image bel

Answer 1

Creating triangles (or other shapes - pentagons, hexagons, octagons, decagons, dodecagons, tetradecagons, octadecagons and so on) with a gradient (or any other kind of image background) is really easy with CSS transforms.

But in this case you don't even need a triangle. You just need to rotate a square pseudo-element by 45deg and apply the gradient on that from corner to corner.

demo

CSS:

.warn {
  position: relative;
  margin: 0 auto;
  border: solid 1px darkred;
  width: 12em; height: 3em;
  border-radius: .2em;
  background: linear-gradient(lightcoral, firebrick);
}
.warn:before {
  position: absolute;
  top: 50%; left: 0;
  margin: -.35em -.45em;
  border-left: inherit; border-bottom: inherit;
  /* pick width & height such that 
     the diagonal of the square is 1em = 1/3 the height of the warn bubble */
  width: .7em; height: .7em;
  border-radius: 0 0 0 .2em;
  transform: rotate(45deg);
  background: linear-gradient(-45deg, firebrick -100%, lightcoral 200%);
  content: '';
}