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                @layer type {
  div {
    font-weight: bold;
    font-size: 1.3em;

@layer color {
  body {
    background: cornsilk!important;
  div {
    color: rebeccapurple;

@layer borders {
  div {
    padding: 1rem;
    border: 1px solid red;

body {
  background: pink;


                // create new attributeSheet
const layers = {}

// Loop through all stylesheets
document?.styleSheets && [...document.styleSheets].forEach((sheet) => {
  try {
    // try to read the sheet rules
    if(sheet?.rules && [...sheet.rules].some(rule => rule instanceof CSSLayerBlockRule)) {
      // loop through the rules (aka layers)
      for( const rule of [...sheet.rules] ) {
        // create a new stylesheet per layer
        if(rule instanceof CSSLayerBlockRule){
          let newSheet = new CSSStyleSheet()
          // add the new sheet to our cached list of layers
          layers[] = newSheet
          // delete the rule from the stylesheet
  } catch(e) {

// add the layers to our adoptedStylesheets
document.adoptedStyleSheets = Object.values(layers);

// generate our checkboxes for each layer
if(Object.values(layers).length > 1) {
  let checkboxes = ``;
  Object.keys(layers).forEach(layer => { checkboxes += `<input id="${layer}" type="checkbox" checked><label for="${layer}">${layer}</label>` })
  const tmpl = `<fieldset id="layers">${checkboxes}</fieldset>`
  document.body.insertAdjacentHTML('beforeBegin', tmpl)

  // bind onchange handlers
  const inputs = document.querySelectorAll('#layers input')
  inputs.forEach( input => {
    input.addEventListener('change', (event) => {
      // get list of active layers
      const activeLayers = [...inputs].filter(el => el.checked).map(el =>
      // because sheet.disabled pops adoptedStylesheets off the stack, 
      // replace all the adoptedStylesheets with only the cached list of active layers
      document.adoptedStyleSheets = => layers[activeLayer])
    } )