Userscript: Anti-Keyboard-Zoom for Safari iOS

safariAntiZoom.js

// ==UserScript==
// @name           Dynamic Anti-AutoZoom
// @namespace      vet.skynet.userscripts
// @author         userscripts@skynet.vet
// @match          *://*/*
// @run-at         document-start
// ==/UserScript==

(function () {
  function updateRule() {
    const scale = window.visualViewport?.scale || 1;
    const targetSize = 16 / scale;

    const id = 'safari-dynamic-antizoom-style';
    document.getElementById(id)?.remove();

    const style = document.createElement('style');
    style.id = id;
    style.textContent = `
      input:focus,
      textarea:focus,
      [contenteditable]:focus {
        font-size: ${targetSize}px !important;
        line-height: 1.2 !important;
      }
    `;
    document.documentElement.appendChild(style);
  }

  updateRule();

  if (window.visualViewport) {
    window.visualViewport.addEventListener('resize', updateRule);
    window.visualViewport.addEventListener('scroll', updateRule);
  }
})();