FR v4: Remove tons of redundant CSS variables

[dmitrystas]

At the moment (v3.4.3) all core plugins that use variables generate a lot of redundant styles. For example, Scale plugin generate
transform: translate(var(--tw-translate-x), var(--tw-translate-y)) rotate(var(--tw-rotate)) skewX(var(--tw-skew-x)) skewY(var(--tw-skew-y)) scaleX(var(--tw-scale-x)) scaleY(var(--tw-scale-y));
for each of all scale-* classes. Translate plugin (as well as all other transform plugins) does the same. All filter plugins (dropShadow, etc) generate
filter: var(--tw-blur) var(--tw-brightness) var(--tw-contrast) var(--tw-grayscale) var(--tw-hue-rotate) var(--tw-invert) var(--tw-saturate) var(--tw-sepia) var(--tw-drop-shadow);
Before/After generate content: var(--tw-content);, etc.

My suggestion is to generate transform (filter, etc) property (with init variable values) only for main .transform class, and then Scale plugin will only set --tw-scale-x / --tw-scale-y variables. In other words

<div class="transform scale-y-75 md:scale-y-90">test</div>

will generate

.transform {
  --tw-translate-x: 0;
  --tw-translate-y: 0;
  --tw-rotate: 0;
  --tw-skew-x: 0;
  --tw-skew-y: 0;
  --tw-scale-x: 1;
  --tw-scale-y: 1;
  transform: translate(var(--tw-translate-x), var(--tw-translate-y)) rotate(var(--tw-rotate)) skewX(var(--tw-skew-x)) skewY(var(--tw-skew-y)) scaleX(var(--tw-scale-x)) scaleY(var(--tw-scale-y));
}

.scale-y-75 {
  --tw-scale-y: .75;
}

@media .... {
  .md\:scale-y-90 {
    --tw-scale-y: .9;
  }
}

instead

.scale-y-75, .md\:scale-y-90 {
    --translate-x: 0;
    --translate-y: 0;
    --rotate: 0;
    --skew-x: 0;
    --skew-y: 0;
    --scale-x: 1;
    --scale-y: 1;
}

.scale-y-75 {
    --tw-scale-y: .75;
    transform: translate(var(--tw-translate-x), var(--tw-translate-y)) rotate(var(--tw-rotate)) skewX(var(--tw-skew-x)) skewY(var(--tw-skew-y)) scaleX(var(--tw-scale-x)) scaleY(var(--tw-scale-y)); /* REDUNDANT */
}

@media .... {
  .md\:scale-y-90 {
    --tw-scale-y: .9;
    transform: translate(var(--tw-translate-x), var(--tw-translate-y)) rotate(var(--tw-rotate)) skewX(var(--tw-skew-x)) skewY(var(--tw-skew-y)) scaleX(var(--tw-scale-x)) scaleY(var(--tw-scale-y)); /* REDUNDANT */
  }
}

The same approach applies to all other plugins plugins that use variables. For example, for Before/After we could totally remove variable and set content only for content-[''] class (or just content for default '' value), and then before:somePlugin, before:anotherOnePlugin will only set their (plugins) properties:

<div class="content-[''] before:absolute before:bg-pink-500>test</div>

will generate

.content\-\[''\]::before {
  content: '';
}

.before\:absolute::before {
  position: absolute;
}

.before\:bg-pink-500::before {
  background....
}

instead

:before,
:after {
  --tw-content: "";
}

.before\:absolute::before {
  content: var(--tw-content); /* REDUNDANT */
  position: absolute;
}

.before\:bg-pink-500::before {
  content: var(--tw-content); /* REDUNDANT */
  background....
}