PostCSS cssnext Syntax Cheat Sheet

[!NOTE] postcss-cssnext has been deprecated in favor of postcss-preset-env. This cheat sheet serves as a reference for legacy projects utilizing cssnext syntaxes.

CSS Custom Properties (Variables)

:root {
  --primary-color: #3b82f6;
  --spacing-base: 1rem;
}

.button {
  background: var(--primary-color);
  padding: var(--spacing-base);
}

---

Custom Selectors & Nesting

Custom Selectors

@custom-selector :--heading h1, h2, h3, h4, h5, h6;

:--heading {
  margin-top: 0;
  font-weight: 700;
}

Native CSS Nesting

.card {
  padding: 1rem;

  & .title {
    font-size: 1.25rem;
  }

  &:hover {
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  }
}

---

Custom Media Queries

@custom-media --small-viewport (max-width: 30em);
@custom-media --large-viewport (min-width: 60em);

@media (--small-viewport) {
  body {
    font-size: 14px;
  }
}

---

Functional Color Functions

a {
  /* Relative adjustments */
  color: color(var(--primary-color) alpha(-20%));
  color: color(red tint(20%));    /* Lighten */
  color: color(blue shade(30%));  /* Darken */

  /* Grayscale shortcuts */
  background: gray(50);          /* rgb(50, 50, 50) */
  background: gray(80%);         /* 80% lightness */
}