トゥートを別タブで開いた時に狭くします。

mastodon_open_narrow_page.user.js

// ==UserScript==
// @name        [Mastodon] open permalink in a narrow page
// @namespace   hen.acho.co
// @include     https://pawoo.net/web/*
// @include     https://mstdn.maud.io/*
// @version     1.230124
// @description view only toot
// @downloadURL https://gist.github.com/pacochi/a17600139f65e57cd2b2a65b6502796a/raw/mastodon_open_narrow_page.user.js
// @run-at      document-idle
// @grant       none
// ==/UserScript==

document.querySelector('#mastodon')?.addEventListener('click', e => {

	if (e.target.nodeName == 'TIME' && e.target.parentNode.className == 'status__relative-time') {

		e.stopPropagation();
		e.preventDefault();
		//window.open(e.target.parentNode.href, '_blank', 'width=600');
		const url = e.target.parentNode.href;
		const win = window.open();
		const E = (name, attr) => win.document.body.append(Object.assign(win.document.createElement(name), attr));
		E('input', { value: url, style: `
		 width: 600px;
		 display: block;
		 margin: 0px auto;
		`, onclick: e => {
			e.target.select();
			win.document.execCommand('copy');
			e.stopPropagation();
		} });
		E('iframe', { src: url, style: `
		 width: 600px;
		 height: 95%;
		 display: block;
		 margin: 0px auto;
		`});
		win.document.title = e.target.closest('[aria-label]').getAttribute('aria-label');

	}

});