fixed highlighting and styles

site/src/jsTest/kotlin/LyngHighlightTest.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class LyngHighlightTest {
+    @Test
+    fun highlightsLyngFencedBlock() {
+        val md = """
+            ```lyng
+            and or not constructor property a+b
+            ```
+        """.trimIndent()
+        val html = renderMarkdown(md)
+
+        // Should produce span classes for keywords and operator
+        assertTrue(html.contains("hl-kw"), "Expected keyword class in highlighted Lyng block: $html")
+        assertTrue(html.contains("hl-op"), "Expected operator class in highlighted Lyng block: $html")
+        // Ensure code is inside <pre><code ... language-lyng>
+        assertTrue(html.contains("language-lyng", ignoreCase = true), "Expected language-lyng class retained: $html")
+    }
+
+    @Test
+    fun nonLyngBlocksAreUntouched() {
+        val md = """
+            ```kotlin
+            println("Hi")
+            ```
+        """.trimIndent()
+        val html = renderMarkdown(md)
+        // Should not include our Lyng-specific classes
+        assertFalse(html.contains("hl-kw"), "Non-Lyng block should not be Lyng-highlighted: $html")
+        assertTrue(html.contains("<pre"), "Expected <pre> present: $html")
+    }
+
+    @Test
+    fun escapesAngleBracketsInsideSpans() {
+        val md = """
+            ```lyng
+            a<b
+            ```
+        """.trimIndent()
+        val html = renderMarkdown(md)
+        // the '<' should be escaped in HTML
+        assertTrue(html.contains("&lt;"), "Expected escaped < inside highlighted HTML: $html")
+    }
+}