Optize font performance

assets/page.html

@@ -5,6 +5,8 @@
         <meta name="viewport" content="width=device-width, initial-scale=1" />
         <title>{{.Title}}</title>
         <link rel="icon" href="/_/favicon.ico" />
+        <link rel="preload" href="/_/fonts/IosevkaEtoile.woff2" as="font" type="font/woff2" crossorigin />
+        <link rel="preload" href="/_/fonts/IosevkaSlab.woff2" as="font" type="font/woff2" crossorigin />
         <link rel="stylesheet" href="/_/style.css" />
         <script src="/_/global-shortcuts.js"></script>
     </head>

assets/style.css

@@ -2,10 +2,12 @@
 @font-face {
     font-family: "Iosevka Etoile";
     src: url("/_/fonts/IosevkaEtoile.woff2") format("woff2");
+    font-display: swap;
 }
 @font-face {
     font-family: "Iosevka Slab";
     src: url("/_/fonts/IosevkaSlab.woff2") format("woff2");
+    font-display: swap;
 }
 
 /* === Theme === */

main.go

@@ -54,7 +54,13 @@ func main() {
 	h := &handler{root: root, user: *user, pass: *pass}
 
 	staticFS, _ := fs.Sub(assets, "assets")
-	http.Handle("/_/", http.StripPrefix("/_/", http.FileServer(http.FS(staticFS))))
+	static := http.StripPrefix("/_/", http.FileServer(http.FS(staticFS)))
+	http.Handle("/_/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.HasPrefix(r.URL.Path, "/_/fonts/") {
+			w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
+		}
+		static.ServeHTTP(w, r)
+	}))
 	http.Handle("/", h)
 
 	log.Printf("datascape listening on %s, wiki at %s", *addr, root)