fix: resolve sidebar overlap and top-bar layout

Added padding-left to main-content and implemented missing top-bar and content-body styles to ensure correct layout with fixed sidebar.

static/css/dashboard.css

@@ -625,17 +625,48 @@ body {
 
 /* Main Content Area */
 .main-content {
-    margin-left: 260px;
+    padding-left: 260px;
     flex: 1;
     min-height: 100vh;
-    transition: all 0.3s;
+    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     display: flex;
     flex-direction: column;
     background-color: var(--bg-primary);
 }
 
-.sidebar.collapsed ~ .main-content {
-    margin-left: 80px;
+.sidebar.collapsed + .main-content {
+    padding-left: 80px;
+}
+
+.top-bar {
+    height: 70px;
+    background: var(--bg0);
+    border-bottom: 1px solid var(--bg2);
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 var(--spacing-xl);
+    position: sticky;
+    top: 0;
+    z-index: 100;
+}
+
+.top-bar .page-title h2 {
+    font-size: 1.25rem;
+    font-weight: 700;
+    color: var(--fg0);
+}
+
+.top-bar-actions {
+    display: flex;
+    align-items: center;
+    gap: var(--spacing-lg);
+}
+
+.content-body {
+    padding: var(--spacing-xl);
+    flex: 1;
+    position: relative;
 }
 
 .top-nav {