add common pallete for public side

src/webui/www/public/css/login.css

@@ -32,7 +32,7 @@ body {
 }
 
 #error_msg {
-    color: #f00;
+    color: var(--color-text-red);
 }
 
 #login {

src/webui/www/public/css/noscript.css

@@ -3,6 +3,6 @@
 }
 
 #noscript {
-    color: #f00;
+    color: var(--color-text-red);
     text-align: center;
 }

src/webui/www/public/css/palette.css

@@ -0,0 +1,24 @@
+/* Adaptive color palette #19844 */
+
+/* Default rules */
+* {
+    --color-text-red: hsl(0deg 100% 65%);
+}
+
+:root {
+    color-scheme: light dark;
+}
+
+/* Light corrections */
+@media (prefers-color-scheme: light) {
+    :root {
+        color-scheme: light;
+    }
+}
+
+/* Dark corrections */
+@media (prefers-color-scheme: dark) {
+    :root {
+        color-scheme: dark;
+    }
+}

src/webui/www/public/index.html

@@ -6,6 +6,7 @@
     <title>qBittorrent QBT_TR(Web UI)QBT_TR[CONTEXT=OptionsDialog]</title>
     <link rel="icon" type="image/png" href="images/qbittorrent32.png" />
     <link rel="icon" type="image/svg+xml" href="images/qbittorrent-tray.svg" />
+    <link rel="stylesheet" type="text/css" href="css/palette.css?v=${CACHEID}" />
     <link rel="stylesheet" type="text/css" href="css/login.css?v=${CACHEID}" />
     <noscript>
         <link rel="stylesheet" type="text/css" href="css/noscript.css?v=${CACHEID}" />