assets/js/embed.host.js

import iframeResize from 'iframe-resizer/js/iframeResizer'

var iframes = iframeResize(
  {
    heightCalculationMethod: 'taggedElement',
    onInit: onInit,
    checkOrigin: false
  },
  '[plausible-embed]'
)

function onInit() {
  var iframe = iframes[0]
  var styles = iframe.getAttribute('styles')

  if (styles) {
    iframe.iFrameResizer.sendMessage({
      type: 'load-custom-styles',
      opts: {
        styles: styles
      }
    })
  }
}