T45 Website: a home in motion and every story live, chapters on the left

frontend/src/theme.ts

@@ -0,0 +1,20 @@
+export type Mode = "light" | "dark";
+
+const listeners = new Set<(mode: Mode) => void>();
+
+export function mode(): Mode {
+  return document.documentElement.classList.contains("dark") ? "dark" : "light";
+}
+
+export function setMode(next: Mode): void {
+  document.documentElement.classList.toggle("dark", next === "dark");
+  try {
+    localStorage.setItem("ely-theme", next);
+  } catch {}
+  listeners.forEach((listen) => listen(next));
+}
+
+export function onMode(listen: (mode: Mode) => void): () => void {
+  listeners.add(listen);
+  return () => listeners.delete(listen);
+}