A somewhat nicer frosted glass effect using SVG filters

glass.js

let template = document.createElement("template")

template.innerHTML = `
<svg>
  <defs>
    <filter id="zoom">
      <feTurbulence type="turbulence" baseFrequency="0.05" numOctaves="2" />
      <feGaussianBlur in="distorted" stdDeviation="2" result="turbulence" />
      <feDisplacementMap in2="turbulence" in="SourceGraphic" scale="10" xChannelSelector="R" yChannelSelector="G" result="distorted"/>
      <feGaussianBlur in="distorted" stdDeviation="2" />
      <feColorMatrix type="matrix" values="
       .98  0  0  0  0
        0   1  0  0  0
       .02 .02  1  0  0
        0   0  0  1  0" />
    </filter>
  </defs>
</svg>
<div style="position: fixed; left: 0rem; top: 0rem; bottom: 0rem; right: 0rem; pointer-events: none; z-index: 99; backdrop-filter: url(#zoom)"></div>
`

document
  .querySelector("body")
  .appendChild(template.content.cloneNode(true))