fix: backwater curves: restore filled area under water line

refs #554

src/app/components/remous-results/remous-results.component.ts

@@ -435,6 +435,11 @@ export class RemousResultsComponent extends ResultsComponentDirective implements
                         }
                     }
                 }
+            },
+            elements: {
+                line: {
+                    fill: true
+                }
             }
         };
 
@@ -473,6 +478,11 @@ export class RemousResultsComponent extends ResultsComponentDirective implements
                             }
                         }
                     }
+                },
+                elements: {
+                    line: {
+                        fill: true
+                    }
                 }
             };
         }