@keyframes

Stylus supports @keyframes both with curly braces or without them, you can also use interpolation both in names or steps of @keyframes:

$keyframe-name = pulse
@keyframes {$keyframe-name}
  for i in 0..10
    {10% * i}
      opacity (i/10)

$keyframe-name = pulse
@keyframes {$keyframe-name}
  for i in 0..10
    {10% * i}
      opacity (i/10)

Yielding (expanded prefixes ommited):

@keyframes pulse {
  0% {
    opacity: 0;
  }
  20% {
    opacity: 0.2;
  }
  40% {
    opacity: 0.4;
  }
  60% {
    opacity: 0.6;
  }
  80% {
    opacity: 0.8;
  }
  100% {
    opacity: 1;
  }
}

@keyframes pulse {
  0% {
    opacity: 0;
  }
  20% {
    opacity: 0.2;
  }
  40% {
    opacity: 0.4;
  }
  60% {
    opacity: 0.6;
  }
  80% {
    opacity: 0.8;
  }
  100% {
    opacity: 1;
  }
}

Expansion

By using @keyframes, your rules are automatically expanded to the vendor prefixes defined by the vendors variable (default: moz webkit o ms official). This means we can alter it at any time for the expansion to take effect immediately.

Note that expansion of @keyframes to the prefixed at-rules would be removed from the Stylus 1.0 when we'd get to it

For example, consider the following:

@keyframes foo {
  from {
    color: black
  }
  to {
    color: white
  }
}

@keyframes foo {
  from {
    color: black
  }
  to {
    color: white
  }
}

This expands to our three default vendors, and the official syntax:

@-moz-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@-webkit-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@-o-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}

@-moz-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@-webkit-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@-o-keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}
@keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}

If we wanted to limit to the official syntax only, simply alter vendors:

vendors = official

@keyframes foo {
  from {
    color: black
  }
  to {
    color: white
  }
}

vendors = official

@keyframes foo {
  from {
    color: black
  }
  to {
    color: white
  }
}

Yielding:

@keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}

@keyframes foo {
  from {
    color: #000;
  }
  to {
    color: #fff;
  }
}

@keyframes #

Expansion #

@keyframes

Expansion