added custom_css in config

config.toml

@@ -13,6 +13,29 @@ success_message = "Success sending submission"
 # Text displayed in a popup shown after submitting, in case of an error
 error_message = "Error while sending submission"
 
+custom_css = """
+:root {
+    --bg-body: #0f172a;
+    --bg-card: #1e293b;
+    --bg-input: #0f172a;
+
+    --text-main: #f8fafc;
+    --text-muted: #94a3b8;
+    --text-inv: #ffffff;
+
+    --primary: #6366f1;
+    --primary-hover: #818cf8;
+    --primary-glow: rgba(99, 102, 241, 0.25);
+
+    --border-base: #334155;
+    --border-focus: #6366f1;
+
+    --radius-lg: 16px;
+    --radius-md: 10px;
+    --shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
+}
+"""
+
 # Standard single-line input
 [[fields]]
 name = "username"

src/handlers.rs

@@ -52,6 +52,7 @@ pub struct AppConfig {
     pub success_message: String,
     pub error_message: String,
     pub fields: Vec<FieldDef>,
+    pub custom_css: Option<String>,
 }
 
 #[derive(Clone)]
@@ -71,6 +72,7 @@ pub async fn render_form(State(state): State<AppState>) -> impl IntoResponse {
         error_message: &'a str,
         fields: &'a [FieldDef],
         lang: &'a str,
+        custom_css: &'a str,
     }
 
     let tmpl = FormTemplate {
@@ -80,6 +82,7 @@ pub async fn render_form(State(state): State<AppState>) -> impl IntoResponse {
         error_message: &state.cfg.error_message,
         fields: &state.cfg.fields,
         lang: "en",
+        custom_css: state.cfg.custom_css.as_deref().unwrap_or(""),
     };
     match tmpl.render() {
         Ok(html) => Html(html).into_response(),

templates/_layout.html

@@ -11,6 +11,7 @@
     <style>
       /*<![CDATA[*/
           {%~ include "_layout.css" ~%}
+          {{ custom_css | safe }}
       /*]]>*/
     </style>
 </head>