訂正>>669

// ==UserScript==
// @name strong zoom
// @namespace local
// @version 1.0
// @description force zoom enable
// @match *://*/*
// @run-at document-end
// @grant none
// ==/UserScript==

(function () {
function applyZoom() {
let meta = document.querySelector('meta[name="viewport"]');
if (meta) {
meta.content = "width=device-width, initial-scale=1.0, maximum-scale=10.0, user-scalable=yes";
} else {
let m = document.createElement("meta");
m.name = "viewport";
m.content = "width=device-width, initial-scale=1.0, maximum-scale=10.0, user-scalable=yes";
document.head.appendChild(m);
}
}

applyZoom();

const observer = new MutationObserver(applyZoom);
observer.observe(document.documentElement, {
childList: true,
subtree: true
});
})();