Cookie instructions (sveltejs#223)

* fix chrome 3P cookie instructions - closes sveltejs#60

* firefox instructions

Author: Rich-Harris

src/routes/tutorial/[slug]/Loading.svelte

@@ -30,16 +30,29 @@
 						third party cookies
 					</a> are enabled for this site, and disable Enhanced Tracking Protection.
 				</p>
+				<p>
+					If you have 'Delete cookies and site data when Firefox is closed' enabled in
+					<code>about:preferences#privacy</code>, make sure <code>learn.svelte.dev</code> is included
+					as an exception.
+				</p>
 			{:else if /chrome/i.test(navigator.userAgent) && !/edg/i.test(navigator.userAgent)}
 				<p>
-					We couldn't start the app. Please ensure
-					<a
-						target="_blank"
-						rel="noreferrer"
-						href="https://support.mozilla.org/en-US/kb/third-party-cookies-firefox-tracking-protection"
+					We couldn't start the app. Please ensure third party cookies are enabled for this site —
+					click the
+					<svg
+						xmlns="http://www.w3.org/2000/svg"
+						viewBox="0 0 24 24"
+						style="width: 1em; height: 1em; position: relative; top: 0.1em; margin: 0 0.2em; transform: scale(1.2)"
 					>
-						third party cookies
-					</a> are enabled for this site.
+						<title>eye</title>
+						<path
+							fill="#666"
+							d="M11.83,9L15,12.16C15,12.11 15,12.05 15,12A3,3 0 0,0 12,9C11.94,9 11.89,9 11.83,9M7.53,9.8L9.08,11.35C9.03,11.56 9,11.77 9,12A3,3 0 0,0 12,15C12.22,15 12.44,14.97 12.65,14.92L14.2,16.47C13.53,16.8 12.79,17 12,17A5,5 0 0,1 7,12C7,11.21 7.2,10.47 7.53,9.8M2,4.27L4.28,6.55L4.73,7C3.08,8.3 1.78,10 1,12C2.73,16.39 7,19.5 12,19.5C13.55,19.5 15.03,19.2 16.38,18.66L16.81,19.08L19.73,22L21,20.73L3.27,3M12,7A5,5 0 0,1 17,12C17,12.64 16.87,13.26 16.64,13.82L19.57,16.75C21.07,15.5 22.27,13.86 23,12C21.27,7.61 17,4.5 12,4.5C10.6,4.5 9.26,4.75 8,5.2L10.17,7.35C10.74,7.13 11.35,7 12,7Z"
+						/>
+					</svg>
+					icon in the URL bar or go to
+					<code>chrome://settings/cookies</code> and add <code>learn.svelte.dev</code> to 'Sites that
+					can always use cookies'.
 				</p>
 			{:else}
 				<p>