diff --git a/Bootstrap_new/css/theme-modern.css b/Bootstrap_new/css/theme-modern.css
index a1dc5a4c..992eb59c 100644
--- a/Bootstrap_new/css/theme-modern.css
+++ b/Bootstrap_new/css/theme-modern.css
@@ -265,17 +265,17 @@ h1, h2, h3, h4, h5, h6, .fw-bold, .fw-semibold {
    Section 2 : Sidebar (Navigation Haute Densité)
    ============================================================ */
 #sidebar {
-  width: var(--sidebar-width);
-  background: var(--bg-sidebar);
-  position: fixed;
-  top: var(--header-height);
-  left: 0;
-  height: calc(100vh - var(--header-height));
-  overflow-y: auto;
-  overflow-x: hidden;
-  transition: width var(--transition-slow);
-  z-index: 900;
-  padding: 8px 4px;
+    width: var(--sidebar-width);
+    background: var(--color-primary); /* Charcoal profond pour le contraste */
+    position: fixed;
+    top: var(--header-height);
+    left: 0;
+    height: calc(100vh - var(--header-height));
+    overflow-y: auto;
+    border-right: 1px solid rgba(255, 255, 255, 0.05);
+    transition: width var(--transition-base);
+    z-index: 900;
+    padding: 1rem 0.5rem;
 }
 
 /* Liseré supérieur discret — gris clair */