diff --git a/cli.ts b/cli.ts
index 1f2dfe1..cd48c1a 100644
--- a/cli.ts
+++ b/cli.ts
@@ -19,22 +19,67 @@ function pageToHtml(page: Page) {
 	)
 }
 
-const outDir = "build/web";
-if (!fs.existsSync(outDir)) {
-	fs.mkdirSync(outDir);
-}
-
-for (const page of pages) {
-	const dirSep = page.ref.indexOf("/", 1);
-	if (dirSep !== -1) {
-		const dir = `${outDir}/${page.ref.slice(0, dirSep)}`;
-		if (!fs.existsSync(dir)) {
-			fs.mkdirSync(dir);
-		}
+function assembleResources() {
+	const webDir = "public";
+	const resources = new Map<string, string | Page>();
+	for (const entry of fs.readdirSync(webDir, { recursive: true, withFileTypes: true })) {
+		if (!entry.isFile())
+			continue;
+		const parentPath = entry.parentPath.replace(/\\/g, "/");
+		const ref = `${parentPath.slice(webDir.length)}/${entry.name}`;
+		resources.set(ref, `${parentPath}/${entry.name}`);
 	}
-	console.log(`writing ${outDir}${page.ref}`);
-	fs.writeFileSync(`${outDir}${page.ref}`, pageToHtml(page));
+	for (const page of pages) {
+		if (resources.has(page.ref)) {
+			const existing = resources.get(page.ref)!;
+			const other = typeof existing === "string" ? "a static resource" : `"${existing.title}"`;
+			throw new Error(`ref "${page.ref}" is taken up by both "${page.title}" and ${other}`)
+		}
+		resources.set(page.ref, page);
+	}
+	return resources;
 }
 
-console.log(`writing ${outDir}/style.css`);
-fs.writeFileSync(`${outDir}/style.css`, fs.readFileSync("public/style.css"));
+function build() {
+	const outDir = "build/web";
+	const dirsCreated = new Set<string>()
+	for (const [ref, resource] of assembleResources()) {
+		const refDir = `${outDir}${posix.dirname(ref)}`;
+		if (!dirsCreated.has(refDir)) {
+			fs.mkdirSync(refDir, { recursive: true });
+		}
+		console.log(`writing ${outDir}${ref}`);
+		let content;
+		if (typeof resource === "string") {
+			content = fs.readFileSync(resource);
+		} else {
+			content = pageToHtml(resource);
+		}
+		fs.writeFileSync(`${outDir}${ref}`, content);
+	}
+}
+
+function printUsage() {
+	console.log("Usage: cli.js <cmd>");
+	console.log("    build - Copy resources and generated pages to build directory.");
+}
+
+function main(runtime: string, script: string, args: string[]) {
+	if (!args.length) {
+		printUsage();
+		process.exitCode = 1;
+		return;
+	}
+
+	const [command, ...commandArgs] = args;
+	if (command === "build") {
+		build();
+	} else {
+		console.log(`Error: Unkown sub-command ${command}`);
+		printUsage();
+		process.exitCode = 1;
+	}
+}
+
+const [runtime, script, ...args] = process.argv;
+main(runtime, script, args)
diff --git a/package.json b/package.json
index 01d6d2b..fe91023 100644
--- a/package.json
+++ b/package.json
@@ -6,7 +6,7 @@
 	"main": "build/node/index.js",
 	"scripts": {
 		"prepare": "tsc",
-		"build": "node --enable-source-maps build/node/cli.js",
+		"build": "node --enable-source-maps build/node/cli.js build",
 		"test": "node --test --enable-source-maps --experimental-test-coverage"
 	},
 	"dependencies": {