merged consecutive style elements

lib/single-file/htmlmini.js

@@ -121,7 +121,7 @@ this.htmlmini = this.htmlmini || (() => {
 		}
 	};
 
-	const modules = [collapseBooleanAttributes, mergeTextNodes, collapseWhitespace, removeComments, removeEmptyAttributes, removeRedundantAttributes];
+	const modules = [collapseBooleanAttributes, mergeTextNodes, collapseWhitespace, removeComments, removeEmptyAttributes, removeRedundantAttributes, node => mergeElements(node, "STYLE", (node, previousSibling) => node.media == previousSibling.media)];
 
 	return {
 		process: (doc, options) => {
@@ -160,6 +160,22 @@ this.htmlmini = this.htmlmini || (() => {
 		}
 	}
 
+	function mergeElements(node, tagName, testFn) {
+		if (node.nodeType == Node.ELEMENT_NODE && node.tagName == tagName) {
+			let previousSibling = node.previousSibling;
+			let previousSiblings = [];
+			while (previousSibling && previousSibling.nodeType == Node.TEXT_NODE && !previousSibling.textContent.trim()) {
+				previousSiblings.push(previousSibling);
+				previousSibling = previousSibling.previousSibling;
+			}
+			if (previousSibling && previousSibling.nodeType == Node.ELEMENT_NODE && previousSibling.tagName == node.tagName && testFn(node, previousSibling)) {
+				node.textContent = previousSibling.textContent + node.textContent;
+				previousSiblings.forEach(node => node.remove());
+				previousSibling.remove();
+			}
+		}
+	}
+
 	function collapseWhitespace(node, options) {
 		if (node.nodeType == Node.TEXT_NODE) {
 			let element = node.parentElement;
@@ -174,7 +190,7 @@ this.htmlmini = this.htmlmini || (() => {
 				let lastTextContent;
 				while (lastTextContent != textContent) {
 					lastTextContent = textContent;
-					textContent = textContent.replace(/[ \n\t\f\r]+/g, " ");
+					textContent = textContent.replace(/[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+/g, " ");
 				}
 				node.textContent = textContent;
 			}