diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e3bce2e..89e5e89 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -13,7 +13,7 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: temurin
-          java-version: 16
+          java-version: 11
       - uses: gradle/wrapper-validation-action@v1
       - uses: gradle/gradle-build-action@v2
       - run: ./gradlew check shadowJar
diff --git a/build.gradle.kts b/build.gradle.kts
index 0e28a01..afb4422 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -8,7 +8,7 @@ plugins {
 
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(17))
+        languageVersion.set(JavaLanguageVersion.of(11))
     }
 }
 
diff --git a/src/main/java/ee/ut/dendroloj/GraphGUI.java b/src/main/java/ee/ut/dendroloj/GraphGUI.java
index 448b4ce..73e1a15 100644
--- a/src/main/java/ee/ut/dendroloj/GraphGUI.java
+++ b/src/main/java/ee/ut/dendroloj/GraphGUI.java
@@ -25,39 +25,27 @@ public static void init(double uiScale) {
         Graph graph = new SingleGraph("DendroloJ");
         graph.setAttribute("ui.quality");
         graph.setAttribute("ui.antialias");
-        graph.setAttribute("ui.stylesheet", String.format(Locale.ROOT, """                 
-                edge {
-                    size: %fpx;
-                    text-size: %f;
-                    text-alignment: center;
-                    text-background-mode: plain;
-                    text-background-color: rgba(255, 255, 255, 180);
-                    text-padding: %f;
-                    text-offset: 5, 0;
-                }
-
-                edge .returned {
-                    fill-color: gray;
-                }
-
-                node {
-                    size: %fpx;
-                    text-size: %f;
-                    text-alignment: at-right;
-                    text-background-mode: plain;
-                    text-background-color: rgba(255, 255, 255, 180);
-                    text-padding: %f;
-                    text-offset: 5, 0;
-                }
-
-                node.error {
-                    fill-color: #fa4c29;
-                }
-
-                node:selected {
-                    fill-color: #0096ff;
-                }
-                """, Math.sqrt(uiScale), uiScale * 12, uiScale + 1, Math.sqrt(uiScale) * 10, uiScale * 12, uiScale + 1));
+        graph.setAttribute("ui.stylesheet", String.format(Locale.ROOT,
+                "edge {" +
+                        " size: %fpx; text-size: %f; text-alignment: center;" +
+                        " text-background-mode: plain; text-background-color: rgba(255, 255, 255, 180);" +
+                        " text-padding: %f; text-offset: 5, 0;" +
+                        "}" +
+                        "edge .returned {" +
+                        " fill-color: gray;" +
+                        "}" +
+                        "node {" +
+                        " size: %fpx; text-size: %f; text-alignment: at-right;" +
+                        " text-background-mode: plain; text-background-color: rgba(255, 255, 255, 180);" +
+                        " text-padding: %f; text-offset: 5, 0;" +
+                        "}" +
+                        "node.error {" +
+                        " fill-color: #fa4c29;" +
+                        "}" +
+                        "node:selected {" +
+                        " fill-color: #0096ff;" +
+                        "}",
+                Math.sqrt(uiScale), uiScale * 12, uiScale + 1, Math.sqrt(uiScale) * 10, uiScale * 12, uiScale + 1));
 
         JSlider stepSlider = new JSlider();
         stepSlider.setPaintTicks(true);
diff --git a/src/main/java/ee/ut/dendroloj/SimpleTreeLayout.java b/src/main/java/ee/ut/dendroloj/SimpleTreeLayout.java
index 0af0e50..725a832 100644
--- a/src/main/java/ee/ut/dendroloj/SimpleTreeLayout.java
+++ b/src/main/java/ee/ut/dendroloj/SimpleTreeLayout.java
@@ -9,6 +9,7 @@
 import javax.swing.*;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 
 class SimpleTreeLayout {
@@ -83,11 +84,20 @@ private static void setActiveStep(int newActiveStep) {
         activeStep = newActiveStep;
     }
 
-    private record NodeMetaWrapper(CallTreeNode node, List<NodeMetaWrapper> children, double reservedWidth) {
+    private static class NodeMetaWrapper {
+        public final CallTreeNode node;
+        public final List<NodeMetaWrapper> children;
+        public final double reservedWidth;
+
+        public NodeMetaWrapper(CallTreeNode node, List<NodeMetaWrapper> children, double reservedWidth) {
+            this.node = node;
+            this.children = children;
+            this.reservedWidth = reservedWidth;
+        }
     }
 
     private static NodeMetaWrapper wrap(CallTreeNode node) {
-        List<NodeMetaWrapper> children = node.childStream().map(SimpleTreeLayout::wrap).toList();
+        List<NodeMetaWrapper> children = node.childStream().map(SimpleTreeLayout::wrap).collect(Collectors.toList());
         double sum = children.stream().mapToDouble(c -> c.reservedWidth).sum();
 
         return new NodeMetaWrapper(node, children, Math.max(1d, sum));
@@ -118,7 +128,7 @@ private static void updateGraph(NodeMetaWrapper meta, boolean hideNewElements, L
         double reserve = meta.reservedWidth / meta.children.size();
         double padding = reserve / 2;
         for (int i = 0; i < meta.children.size(); i++) {
-            updateGraph(meta.children().get(i), hideNewElements, newElements,
+            updateGraph(meta.children.get(i), hideNewElements, newElements,
                     leftBoundary + padding + (reserve * i), y - layerHeight, layerHeight, current);
         }
 
diff --git a/src/test/java/OhtlikAsi.java b/src/test/java/OhtlikAsi.java
index 52ec824..d704936 100644
--- a/src/test/java/OhtlikAsi.java
+++ b/src/test/java/OhtlikAsi.java
@@ -1,13 +1,19 @@
 import ee.ut.dendroloj.Grow;
 
-public record OhtlikAsi(String tekst) {
+public class OhtlikAsi {
+        public final String tekst;
+
+        public OhtlikAsi(String tekst) {
+                this.tekst = tekst;
+        }
+
         @Grow
         int fib(int n, OhtlikAsi a) {
             if (n < 2) return n;
             return fib(n - 2, a) + fib(n - 1, a);
         }
 
-        // @Grow annotatsioon toString meetodil mida kutsutakse puu uuendamise ajal.
+        // @Grow annotatsioon toString meetodil mida kutsutakse puu uuendamise ajal
         @Grow
         @Override
         public String toString() {