add support for an override stylesheet which applies to all users

include/functions.php

@@ -7,6 +7,10 @@
 
 	define('COOKIE_LIFETIME_LONG', 86400*365);
 
+	// this CSS file is included for everyone (if it exists in themes.local)
+	// on login, registration, and main (index and prefs) pages
+	define('LOCAL_OVERRIDE_STYLESHEET', '.local-overrides.css');
+
 	$fetch_last_error = false;
 	$fetch_last_error_code = false;
 	$fetch_last_content_type = false;

include/login_form.php

@@ -18,6 +18,10 @@
 
 	} ?>
 
+	<?php if (theme_exists(LOCAL_OVERRIDE_STYLESHEET)) {
+		echo stylesheet_tag(get_theme_path(LOCAL_OVERRIDE_STYLESHEET));
+	} ?>
+
 	<style type="text/css">
 		@media (prefers-color-scheme: dark) {
 			body {

index.php

@@ -44,8 +44,11 @@
 		if ($theme && theme_exists("$theme")) {
 			echo stylesheet_tag(get_theme_path($theme), 'theme_css');
 		}
-	}
-	?>
+	} ?>
+
+	<?php if (theme_exists(LOCAL_OVERRIDE_STYLESHEET)) {
+		echo stylesheet_tag(get_theme_path(LOCAL_OVERRIDE_STYLESHEET));
+	} ?>
 
 	<script type="text/javascript">
 		const __csrf_token = "<?php echo $_SESSION["csrf_token"]; ?>";

prefs.php

@@ -36,8 +36,11 @@
 		if ($theme && theme_exists("$theme")) {
 			echo stylesheet_tag(get_theme_path($theme), 'theme_css');
 		}
-	}
-	?>
+	} ?>
+
+	<?php if (theme_exists(LOCAL_OVERRIDE_STYLESHEET)) {
+		echo stylesheet_tag(get_theme_path(LOCAL_OVERRIDE_STYLESHEET));
+	} ?>
 
 	<script type="text/javascript">
 		const __csrf_token = "<?php echo $_SESSION["csrf_token"]; ?>";

register.php

@@ -98,6 +98,9 @@
 <?php echo javascript_tag("js/common.js") ?>
 <?php echo javascript_tag("lib/prototype.js") ?>
 <?php echo javascript_tag("lib/scriptaculous/scriptaculous.js?load=effects,controls") ?>
+<?php if (theme_exists(LOCAL_OVERRIDE_STYLESHEET)) {
+		echo stylesheet_tag(get_theme_path(LOCAL_OVERRIDE_STYLESHEET));
+} ?>
 </head>
 
 <script type="text/javascript">