fix layout-boxed with default sidebar

build/scss/_main-sidebar.scss

@@ -926,3 +926,17 @@
 .sidebar nav .form-inline {
   margin-bottom: .2rem;
 }
+
+// Sidebar Collapse on Layout Boxed
+
+.layout-boxed {
+  &.sidebar-collapse .main-sidebar {
+    margin-left: 0;
+  }
+  .content-wrapper, 
+  .main-header,
+  .main-footer {
+    z-index: 9999;
+    position: relative;
+  }
+}

dist/css/adminlte.css

@@ -12798,6 +12798,17 @@ body.sidebar-collapse:not(.sidebar-mini-md):not(.sidebar-mini) .main-header::bef
   margin-bottom: .2rem;
 }
 
+.layout-boxed.sidebar-collapse .main-sidebar {
+  margin-left: 0;
+}
+
+.layout-boxed .content-wrapper,
+.layout-boxed .main-header,
+.layout-boxed .main-footer {
+  z-index: 9999;
+  position: relative;
+}
+
 .logo-xs,
 .logo-xl {
   opacity: 1;