PostCSS plugin remove declarations with empty values, except content property.
If you use CSS framework like Bootstrap or Uikit, you can override their variables with empty string to remove declaration which use that variable.
/* Bootstrap scss source */
h1, .h1 { font-size: $h1-font-size; }
h2, .h2 { font-size: $h2-font-size; }
h3, .h3 { font-size: $h3-font-size; }
h4, .h4 { font-size: $h4-font-size; }
h5, .h5 { font-size: $h5-font-size; }
h6, .h6 { font-size: $h6-font-size; }
/* Your scss variables */
$h1-font-size: 32px;
$h2-font-size: 24px;
$h3-font-size: 16px;
$h4-font-size: "";
$h5-font-size: "";
$h6-font-size: "";
/* css output generated from scss */
h1, .h1 { font-size: 32px; }
h2, .h2 { font-size: 24px; }
h3, .h3 { font-size: 16px; }
h4, .h4 { font-size: ""; }
h5, .h5 { font-size: ""; }
h6, .h6 { font-size: ""; }
/* postcss-clear-empty-string */
h1, .h1 { font-size: 32px; }
h2, .h2 { font-size: 24px; }
h3, .h3 { font-size: 16px; }
h4, .h4 { }
h5, .h5 { }
h6, .h6 { }
/* minify */
h1,.h1{font-size:32px}h2,.h2{font-size:24px}h3,.h3{font-size:16px}postcss([ require('postcss-clear-empty-strings') ])See PostCSS docs for examples for your environment.