fixed nav-flat in collapsed sidebar

build/scss/_main-sidebar.scss

@@ -475,6 +475,28 @@
     }
   }
 
+  .nav-icon {
+    @include transition(margin-left $transition-fn $transition-speed);
+  }
+
+  .nav-treeview {
+    .nav-icon {
+      margin-left: -.2rem;
+    }
+  }
+
+  .sidebar-collapse & {
+    .nav-icon {
+      margin-left: .5rem;
+    }
+
+    .nav-treeview {
+      .nav-icon {
+        margin-left: .3rem;
+      }
+    }
+  }
+
   &.nav-sidebar > .nav-item {
     .nav-treeview,
     > .nav-treeview {

build/scss/_mixins.scss

@@ -173,6 +173,18 @@
           visibility: visible;
         }
 
+        .nav-flat {
+          .nav-icon {
+            margin-left: 0;
+          }
+
+          .nav-treeview {
+            .nav-icon {
+              margin-left: -.2rem;
+            }
+          }
+        }
+
         .logo-xs {
           opacity: 0;
           visibility: hidden;

build/scss/_sidebar-mini.scss

@@ -90,6 +90,18 @@
     .nav-sidebar > .nav-item .nav-icon {
       margin-right: 0;
     }
+
+    .nav-flat {
+      .nav-icon {
+        margin-left: .5rem;
+      }
+
+      .nav-treeview {
+        .nav-icon {
+          margin-left: .3rem;
+        }
+      }
+    }
   }
 }