diff --git a/composer.lock b/composer.lock
index c9ed12f..004cda0 100644
--- a/composer.lock
+++ b/composer.lock
@@ -711,16 +711,16 @@
         },
         {
             "name": "league/commonmark",
-            "version": "2.6.0",
+            "version": "2.6.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/thephpleague/commonmark.git",
-                "reference": "d150f911e0079e90ae3c106734c93137c184f932"
+                "reference": "d990688c91cedfb69753ffc2512727ec646df2ad"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/d150f911e0079e90ae3c106734c93137c184f932",
-                "reference": "d150f911e0079e90ae3c106734c93137c184f932",
+                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/d990688c91cedfb69753ffc2512727ec646df2ad",
+                "reference": "d990688c91cedfb69753ffc2512727ec646df2ad",
                 "shasum": ""
             },
             "require": {
@@ -814,7 +814,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2024-12-07T15:34:16+00:00"
+            "time": "2024-12-29T14:10:59+00:00"
         },
         {
             "name": "league/config",
@@ -2106,12 +2106,12 @@
             },
             "type": "library",
             "extra": {
+                "thanks": {
+                    "url": "https://github.com/symfony/contracts",
+                    "name": "symfony/contracts"
+                },
                 "branch-alias": {
                     "dev-main": "2.5-dev"
-                },
-                "thanks": {
-                    "name": "symfony/contracts",
-                    "url": "https://github.com/symfony/contracts"
                 }
             },
             "autoload": {
@@ -2280,12 +2280,12 @@
             },
             "type": "library",
             "extra": {
+                "thanks": {
+                    "url": "https://github.com/symfony/contracts",
+                    "name": "symfony/contracts"
+                },
                 "branch-alias": {
                     "dev-main": "2.5-dev"
-                },
-                "thanks": {
-                    "name": "symfony/contracts",
-                    "url": "https://github.com/symfony/contracts"
                 }
             },
             "autoload": {
@@ -2574,8 +2574,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -2650,8 +2650,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -2728,8 +2728,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -2812,8 +2812,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -2886,8 +2886,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -2962,8 +2962,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -3042,8 +3042,8 @@
             "type": "library",
             "extra": {
                 "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
+                    "url": "https://github.com/symfony/polyfill",
+                    "name": "symfony/polyfill"
                 }
             },
             "autoload": {
@@ -3187,12 +3187,12 @@
             },
             "type": "library",
             "extra": {
+                "thanks": {
+                    "url": "https://github.com/symfony/contracts",
+                    "name": "symfony/contracts"
+                },
                 "branch-alias": {
                     "dev-main": "2.5-dev"
-                },
-                "thanks": {
-                    "name": "symfony/contracts",
-                    "url": "https://github.com/symfony/contracts"
                 }
             },
             "autoload": {
@@ -3650,13 +3650,13 @@
             },
             "type": "library",
             "extra": {
-                "branch-alias": {
-                    "dev-main": "3.x-dev"
-                },
                 "phpstan": {
                     "includes": [
                         "extension.neon"
                     ]
+                },
+                "branch-alias": {
+                    "dev-main": "3.x-dev"
                 }
             },
             "autoload": {
@@ -3929,29 +3929,27 @@
         },
         {
             "name": "doctrine/deprecations",
-            "version": "1.1.3",
+            "version": "1.1.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/doctrine/deprecations.git",
-                "reference": "dfbaa3c2d2e9a9df1118213f3b8b0c597bb99fab"
+                "reference": "31610dbb31faa98e6b5447b62340826f54fbc4e9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/doctrine/deprecations/zipball/dfbaa3c2d2e9a9df1118213f3b8b0c597bb99fab",
-                "reference": "dfbaa3c2d2e9a9df1118213f3b8b0c597bb99fab",
+                "url": "https://api.github.com/repos/doctrine/deprecations/zipball/31610dbb31faa98e6b5447b62340826f54fbc4e9",
+                "reference": "31610dbb31faa98e6b5447b62340826f54fbc4e9",
                 "shasum": ""
             },
             "require": {
                 "php": "^7.1 || ^8.0"
             },
             "require-dev": {
-                "doctrine/coding-standard": "^9",
-                "phpstan/phpstan": "1.4.10 || 1.10.15",
-                "phpstan/phpstan-phpunit": "^1.0",
+                "doctrine/coding-standard": "^9 || ^12",
+                "phpstan/phpstan": "1.4.10 || 2.0.3",
+                "phpstan/phpstan-phpunit": "^1.0 || ^2",
                 "phpunit/phpunit": "^7.5 || ^8.5 || ^9.5",
-                "psalm/plugin-phpunit": "0.18.4",
-                "psr/log": "^1 || ^2 || ^3",
-                "vimeo/psalm": "4.30.0 || 5.12.0"
+                "psr/log": "^1 || ^2 || ^3"
             },
             "suggest": {
                 "psr/log": "Allows logging deprecations via PSR-3 logger implementation"
@@ -3959,7 +3957,7 @@
             "type": "library",
             "autoload": {
                 "psr-4": {
-                    "Doctrine\\Deprecations\\": "lib/Doctrine/Deprecations"
+                    "Doctrine\\Deprecations\\": "src"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -3970,9 +3968,9 @@
             "homepage": "https://www.doctrine-project.org/",
             "support": {
                 "issues": "https://github.com/doctrine/deprecations/issues",
-                "source": "https://github.com/doctrine/deprecations/tree/1.1.3"
+                "source": "https://github.com/doctrine/deprecations/tree/1.1.4"
             },
-            "time": "2024-01-30T19:34:25+00:00"
+            "time": "2024-12-07T21:18:45+00:00"
         },
         {
             "name": "doctrine/instantiator",
@@ -5010,16 +5008,16 @@
         },
         {
             "name": "nikic/php-parser",
-            "version": "v5.3.1",
+            "version": "v5.4.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/nikic/PHP-Parser.git",
-                "reference": "8eea230464783aa9671db8eea6f8c6ac5285794b"
+                "reference": "447a020a1f875a434d62f2a401f53b82a396e494"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/8eea230464783aa9671db8eea6f8c6ac5285794b",
-                "reference": "8eea230464783aa9671db8eea6f8c6ac5285794b",
+                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/447a020a1f875a434d62f2a401f53b82a396e494",
+                "reference": "447a020a1f875a434d62f2a401f53b82a396e494",
                 "shasum": ""
             },
             "require": {
@@ -5062,9 +5060,9 @@
             ],
             "support": {
                 "issues": "https://github.com/nikic/PHP-Parser/issues",
-                "source": "https://github.com/nikic/PHP-Parser/tree/v5.3.1"
+                "source": "https://github.com/nikic/PHP-Parser/tree/v5.4.0"
             },
-            "time": "2024-10-08T18:51:32+00:00"
+            "time": "2024-12-30T11:07:19+00:00"
         },
         {
             "name": "phan/phan",
@@ -7207,16 +7205,16 @@
         },
         {
             "name": "squizlabs/php_codesniffer",
-            "version": "3.11.1",
+            "version": "3.11.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHPCSStandards/PHP_CodeSniffer.git",
-                "reference": "19473c30efe4f7b3cd42522d0b2e6e7f243c6f87"
+                "reference": "1368f4a58c3c52114b86b1abe8f4098869cb0079"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHPCSStandards/PHP_CodeSniffer/zipball/19473c30efe4f7b3cd42522d0b2e6e7f243c6f87",
-                "reference": "19473c30efe4f7b3cd42522d0b2e6e7f243c6f87",
+                "url": "https://api.github.com/repos/PHPCSStandards/PHP_CodeSniffer/zipball/1368f4a58c3c52114b86b1abe8f4098869cb0079",
+                "reference": "1368f4a58c3c52114b86b1abe8f4098869cb0079",
                 "shasum": ""
             },
             "require": {
@@ -7283,7 +7281,7 @@
                     "type": "open_collective"
                 }
             ],
-            "time": "2024-11-16T12:02:36+00:00"
+            "time": "2024-12-11T16:04:26+00:00"
         },
         {
             "name": "symfony/var-dumper",
diff --git a/docs/content/index.md b/docs/content/index.md
index 3bb2b00..c4d0964 100644
--- a/docs/content/index.md
+++ b/docs/content/index.md
@@ -40,13 +40,14 @@ The structure within that directory can be anything.
 
 *[Read more about Templates.](templates.html)*
 
-## Assets (stylesheets and scripts)
+## Assets (stylesheets, scripts, etc.)
 
-Every stylesheet and script in the `assets/` directory
-will be copied to `output/assets/`.
+Every non-page file (CSS, JS, images, etc.) in the `content/` directory
+will be copied to `output/`.
+("Non-page" means anything with a file extension that
+doesn't match the default as defined by the `ext` key in `basildon.yaml`.)
 
-Images should be in the `content/` directory;
-for more information, see the [Content documentation page](content.html).
+For more information, see the [Content documentation page](content.html).
 
 ## Output
 
diff --git a/docs/assets/style.css b/docs/content/style.css
similarity index 100%
rename from docs/assets/style.css
rename to docs/content/style.css
diff --git a/example/assets/style.css b/example/content/style.css
similarity index 100%
rename from example/assets/style.css
rename to example/content/style.css
diff --git a/example/templates/index.html.twig b/example/templates/index.html.twig
index d30b93b..b9921fd 100644
--- a/example/templates/index.html.twig
+++ b/example/templates/index.html.twig
@@ -4,7 +4,7 @@
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>{{ site.title }}</title>
-    <link rel="stylesheet" href="{{ page.link('/assets/style.css') }}" />
+    <link rel="stylesheet" href="{{ page.link('/style.css') }}" />
 </head>
 <body>
     <header class="site-header">
diff --git a/src/Command/BuildCommand.php b/src/Command/BuildCommand.php
index fabbda5..a734783 100644
--- a/src/Command/BuildCommand.php
+++ b/src/Command/BuildCommand.php
@@ -114,33 +114,21 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             $template->render($page);
         }
 
-        // Copy all other content files.
-        $images = new Finder();
+        // Copy all non-page content files.
+        $files = new Finder();
         $dir = $site->getDir();
-        $images->files()
+        $files->files()
             ->in($dir . '/content')
-            ->name('/.*\.(jpg|png|gif|svg|pdf)$/');
-        foreach ($images as $image) {
-            $assetRelativePath = substr($image->getRealPath(), strlen($dir . '/content'));
-            self::writeln('Image: ' . $assetRelativePath);
-            Util::mkdir(dirname($dir . '/output' . $assetRelativePath));
-            copy($image->getRealPath(), $dir . '/output' . $assetRelativePath);
-        }
-
-        // Copy all assets.
-        // @TODO Add processing (LESS etc.).
-        $assetsDir = $site->getDir() . '/assets';
-        if (is_dir($assetsDir)) {
-            $assets = new Finder();
-            $assets->files()
-                ->in($dir . '/assets')
-                ->name('/.*\.(css|js|jpg|png|gif|svg|pdf)/');
-            $assetsOutputDir = $dir . '/output/assets';
-            Util::mkdir($assetsOutputDir);
-            foreach ($assets as $asset) {
-                self::writeln('Asset: /assets/' . $asset->getFilename());
-                copy($asset->getRealPath(), $assetsOutputDir . '/' . $asset->getFilename());
-            }
+            ->notName('*' . $site->getExt());
+        foreach ($files as $file) {
+            $fileRelativePath = substr($file->getRealPath(), strlen($dir . '/content'));
+            $srcPath = $file->getRealPath();
+            $destPath = $dir . '/output' . $fileRelativePath;
+            // if (filesize($srcPath) !== filesize($destPath) || md5_file($srcPath) !== md5_file($destPath) ) {
+            // }
+            self::writeln('Copying file: ' . $fileRelativePath);
+            Util::mkdir(dirname($destPath));
+            copy($srcPath, $destPath);
         }
 
         $outDir = $site->getDir() . '/output/';
diff --git a/src/Twig.php b/src/Twig.php
index 9dd6afd..76aef91 100644
--- a/src/Twig.php
+++ b/src/Twig.php
@@ -408,7 +408,7 @@ public function functionGetFeeds($feedUrls): ?array
     public function functionQrCode(string $text): string
     {
         $qrFilename = md5($text) . '.svg';
-        $assetPath = '/assets/qrcodes/' . $qrFilename;
+        $assetPath = '/qrcodes/' . $qrFilename;
         $filePath = $this->site->getDir() . '/output' . $assetPath;
         $cachePath = $this->site->getDir() . '/cache/qrcodes/' . $qrFilename;
         // If it's already been used in this run, nothing neds to be done.
diff --git a/tests/UtilTest.php b/tests/UtilTest.php
new file mode 100644
index 0000000..d1736ea
--- /dev/null
+++ b/tests/UtilTest.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Test;
+
+use App\Util;
+use PHPUnit\Framework\TestCase;
+
+final class UtilTest extends TestCase
+{
+    /**
+     * @covers App\Util::cleanDir()
+     */
+    public function testCleanDir(): void
+    {
+        $testDir = __DIR__ . '/utiltest';
+        if (!file_exists($testDir)) {
+            mkdir($testDir);
+        }
+        $this->assertDirectoryExists($testDir);
+
+        // Cleaning an empty directory doesn't delete the directory.
+        Util::cleanDir($testDir);
+        $this->assertDirectoryExists($testDir);
+        $this->assertEmpty(glob($testDir . '/*'));
+
+        // Add a file, and clean again.
+        touch($testDir . '/test.txt');
+        $this->assertCount(1, glob($testDir . '/*'));
+        Util::cleanDir($testDir);
+        $this->assertEmpty(glob($testDir . '/*'));
+
+        // Add three files and a directory, and exclude some.
+        touch($testDir . '/test1.txt');
+        touch($testDir . '/excluded.txt');
+        mkdir($testDir . '/excluded/');
+        touch($testDir . '/excluded/lower.txt');
+        $this->assertCount(3, glob($testDir . '/*'));
+        Util::cleanDir($testDir, ['/excluded.*/']);
+        $this->assertCount(2, glob($testDir . '/*'));
+
+        // Clean up.
+        Util::cleanDir($testDir);
+    }
+}