I found the ſ and ct-with-some-kind-of-curved-line-connecting-them really distracting. So, I altered them out, client-side.

I’m already a user of Tampermonkey and Stylus, so it was easy.

First, Tampermonkey:

// ==UserScript==
// @name         Replace Euclid's funky letters
// @namespace    http://tampermonkey.net/
// @version      0.2
// @author       david loyall
// @match        https://www.c82.net/euclid/*
// @require      http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js
// @grant        none
// ==/UserScript==

//Adapted from https://pastebin.com/6MdivF0K
(function() {
    'use strict';
    String.prototype.replaceAll = function(search, replacement) {
        var target = this;
        return target.replace(new RegExp(search, 'g'), replacement);
    };
    var x = document.getElementsByTagName("p");
    for (var ptag of x) {
        ptag.innerHTML = ptag.innerHTML.replaceAll("ſ", "s");
    }
    console.log("userscript [Replace Euclid's funky letters] done.");
})();

Next, Stylus:

[
	{
		"enabled": true,
		"updateUrl": null,
		"md5Url": null,
		"url": null,
		"originalMd5": null,
		"installDate": 1545065506071,
		"name": "www.c82.net",
		"sections": [
			{
				"code": "main {\n    font-feature-settings: normal;\n}",
				"urlPrefixes": [
					"https://www.c82.net/euclid/"
				]
			}
		],
		"id": 1
	}
]