diff --git a/lib/node.cpp b/lib/node.cpp
index 1792746..d1a373b 100644
--- a/lib/node.cpp
+++ b/lib/node.cpp
@@ -1,21 +1,21 @@
-#include "./node.h"
-
-#include <iostream>
-#include <memory>
-
-void Node::Inspect(int indent) {
-
-  if (this->children.size() > 0) {
-    for (int i = 0; i <= indent; i++) {
-      std::cout << "\t";
-    }
-    std::cout << "std::vector<Node> children: " << std::endl;
-  }
-
-  for (const auto &child : this->children) {
-    for (int i = 0; i <= indent; i++) {
-      std::cout << "\t";
-    }
-    child->Inspect(indent + 1);
-  }
-}
+#include "node.h"
+
+#include <iostream>
+#include <memory>
+
+void Node::Inspect(int indent) {
+
+  if (this->children.size() > 0) {
+    for (int i = 0; i <= indent; i++) {
+      std::cout << "\t";
+    }
+    std::cout << "std::vector<Node> children: " << std::endl;
+  }
+
+  for (const auto &child : this->children) {
+    for (int i = 0; i <= indent; i++) {
+      std::cout << "\t";
+    }
+    child->Inspect(indent + 1);
+  }
+}
diff --git a/lib/parser.cpp b/lib/parser.cpp
index 7b70af7..0f563e0 100644
--- a/lib/parser.cpp
+++ b/lib/parser.cpp
@@ -1,36 +1,36 @@
-#include "./parser.h"
-#include "./util.h"
-#include <cctype>
-#include <stdexcept>
-
-using std::string;
-
-Parser::Parser(string input_file_path, string output_file_path) {
-  // NOTE: Remove any white space AROUND the inputs
-  removeWhitespace(input_file_path);
-  removeWhitespace(output_file_path);
-
-  if (input_file_path == "") {
-    throw std::runtime_error("input_file_path cannot be empty");
-  }
-
-  this->input_file_path = input_file_path;
-
-  // NOTE: If the user does not provide an output file, then we should construct
-  // one using the input file with .md swapped with the extension.
-  if (output_file_path == "") {
-    int ext_idx = input_file_path.find_last_of('.');
-    string output_cleaned = input_file_path.substr(0, ext_idx) + ".html";
-    this->output_file_path = output_cleaned;
-    return;
-  }
-
-  this->output_file_path = output_file_path;
-}
-
-void Parser::Inspect() {
-  std::cout << "std::string input_file_path: " << this->input_file_path
-            << std::endl;
-  std::cout << "std::string output_file_path: " << this->output_file_path
-            << std::endl;
-}
+#include "parser.h"
+#include "util.h"
+#include <cctype>
+#include <stdexcept>
+
+using std::string;
+
+Parser::Parser(string input_file_path, string output_file_path) {
+  // NOTE: Remove any white space AROUND the inputs
+  removeWhitespace(input_file_path);
+  removeWhitespace(output_file_path);
+
+  if (input_file_path == "") {
+    throw std::runtime_error("input_file_path cannot be empty");
+  }
+
+  this->input_file_path = input_file_path;
+
+  // NOTE: If the user does not provide an output file, then we should construct
+  // one using the input file with .md swapped with the extension.
+  if (output_file_path == "") {
+    int ext_idx = input_file_path.find_last_of('.');
+    string output_cleaned = input_file_path.substr(0, ext_idx) + ".html";
+    this->output_file_path = output_cleaned;
+    return;
+  }
+
+  this->output_file_path = output_file_path;
+}
+
+void Parser::Inspect() {
+  std::cout << "std::string input_file_path: " << this->input_file_path
+            << std::endl;
+  std::cout << "std::string output_file_path: " << this->output_file_path
+            << std::endl;
+}
diff --git a/lib/structureNode.cpp b/lib/structureNode.cpp
new file mode 100644
index 0000000..6d4d8f4
--- /dev/null
+++ b/lib/structureNode.cpp
@@ -0,0 +1 @@
+#include "structureNode.h"
diff --git a/lib/structureNode.h b/lib/structureNode.h
new file mode 100644
index 0000000..576de51
--- /dev/null
+++ b/lib/structureNode.h
@@ -0,0 +1,13 @@
+#ifndef STRUCTURENODE_H
+#define STRUCTURENODE_H
+
+#include "node.h"
+
+class StructureNode : public Node {};
+
+class ListNode : public StructureNode {};
+class HeadingNode : public StructureNode {};
+class DocumentNode : public StructureNode {};
+class ParagraphNode : public StructureNode {};
+
+#endif
diff --git a/lib/util.cpp b/lib/util.cpp
index be27900..a63a079 100644
--- a/lib/util.cpp
+++ b/lib/util.cpp
@@ -1,24 +1,24 @@
-#include "./util.h"
-
-void removeTrailingWhitespace(std::string &input) {
-  size_t start = input.find_first_not_of(" \t\n\r\f\v");
-  if (start != std::string::npos) {
-    input.erase(0, start);
-  } else {
-    input.clear();
-  }
-}
-
-void removeLeadingWhitespace(std::string &input) {
-  size_t end = input.find_last_not_of(" \t\n\r\f\v");
-  if (end != std::string::npos) {
-    input.erase(end + 1);
-  } else {
-    input.clear();
-  }
-}
-
-void removeWhitespace(std::string &input) {
-  removeLeadingWhitespace(input);
-  removeTrailingWhitespace(input);
-}
+#include "util.h"
+
+void removeTrailingWhitespace(std::string &input) {
+  size_t start = input.find_first_not_of(" \t\n\r\f\v");
+  if (start != std::string::npos) {
+    input.erase(0, start);
+  } else {
+    input.clear();
+  }
+}
+
+void removeLeadingWhitespace(std::string &input) {
+  size_t end = input.find_last_not_of(" \t\n\r\f\v");
+  if (end != std::string::npos) {
+    input.erase(end + 1);
+  } else {
+    input.clear();
+  }
+}
+
+void removeWhitespace(std::string &input) {
+  removeLeadingWhitespace(input);
+  removeTrailingWhitespace(input);
+}