diff --git a/include/thirdparty/less.php/Visitor.php b/include/thirdparty/less.php/Visitor.php
new file mode 100644
index 0000000..965ddcd
--- /dev/null
+++ b/include/thirdparty/less.php/Visitor.php
@@ -0,0 +1,43 @@
+<?php
+/**
+ * @private
+ */
+class Less_Visitor {
+
+	protected $methods = [];
+	protected $_visitFnCache = [];
+
+	public function __construct() {
+		$this->_visitFnCache = get_class_methods( get_class( $this ) );
+		$this->_visitFnCache = array_flip( $this->_visitFnCache );
+	}
+
+	public function visitObj( $node ) {
+		$funcName = 'visit' . str_replace( [ 'Less_Tree_', '_' ], '', get_class( $node ) );
+		if ( isset( $this->_visitFnCache[$funcName] ) ) {
+			$visitDeeper = true;
+			$this->$funcName( $node, $visitDeeper );
+
+			if ( $visitDeeper ) {
+				$node->accept( $this );
+			}
+
+			$funcName .= "Out";
+			if ( isset( $this->_visitFnCache[$funcName] ) ) {
+				$this->$funcName( $node );
+			}
+
+		} else {
+			$node->accept( $this );
+		}
+
+		return $node;
+	}
+
+	public function visitArray( $nodes ) {
+		foreach ( $nodes as $node ) {
+			$this->visitObj( $node );
+		}
+		return $nodes;
+	}
+}
diff --git a/include/thirdparty/less.php/VisitorReplacing.php b/include/thirdparty/less.php/VisitorReplacing.php
new file mode 100644
index 0000000..484f0e0
--- /dev/null
+++ b/include/thirdparty/less.php/VisitorReplacing.php
@@ -0,0 +1,65 @@
+<?php
+/**
+ * @private
+ */
+class Less_VisitorReplacing extends Less_Visitor {
+
+	public function visitObj( $node ) {
+		$funcName = 'visit' . str_replace( [ 'Less_Tree_', '_' ], '', get_class( $node ) );
+		if ( isset( $this->_visitFnCache[$funcName] ) ) {
+			$visitDeeper = true;
+			$node = $this->$funcName( $node, $visitDeeper );
+
+			if ( $node ) {
+				if ( $visitDeeper && is_object( $node ) ) {
+					$node->accept( $this );
+				}
+
+				$funcName .= "Out";
+				if ( isset( $this->_visitFnCache[$funcName] ) ) {
+					$this->$funcName( $node );
+				}
+			}
+
+		} else {
+			$node->accept( $this );
+		}
+
+		return $node;
+	}
+
+	public function visitArray( $nodes ) {
+		$newNodes = [];
+		foreach ( $nodes as $node ) {
+			$evald = $this->visitObj( $node );
+			if ( $evald ) {
+				if ( is_array( $evald ) ) {
+					self::flatten( $evald, $newNodes );
+				} else {
+					$newNodes[] = $evald;
+				}
+			}
+		}
+		return $newNodes;
+	}
+
+	public function flatten( $arr, &$out ) {
+		foreach ( $arr as $item ) {
+			if ( !is_array( $item ) ) {
+				$out[] = $item;
+				continue;
+			}
+
+			foreach ( $item as $nestedItem ) {
+				if ( is_array( $nestedItem ) ) {
+					self::flatten( $nestedItem, $out );
+				} else {
+					$out[] = $nestedItem;
+				}
+			}
+		}
+
+		return $out;
+	}
+
+}