diff --git a/vendor-overwrites/codemirror/addon/lint/css-lint.js b/vendor-overwrites/codemirror/addon/lint/css-lint.js
index aa4a30c3..f96d383c 100644
--- a/vendor-overwrites/codemirror/addon/lint/css-lint.js
+++ b/vendor-overwrites/codemirror/addon/lint/css-lint.js
@@ -3,100 +3,112 @@
 
 // Depends on csslint.js from https://github.com/stubbornella/csslint
 
-// declare global: CSSLint
+/* global CodeMirror require define */
+/* global CSSLint stylelint stylelintDefaultConfig */
+'use strict';
 
-(function(mod) {
-  if (typeof exports == "object" && typeof module == "object") // CommonJS
-    mod(require("../../lib/codemirror"));
-  else if (typeof define == "function" && define.amd) // AMD
-    define(["../../lib/codemirror"], mod);
-  else // Plain browser env
+(mod => {
+  if (typeof exports === 'object' && typeof module === 'object') {
+    // CommonJS
+    mod(require('../../lib/codemirror'));
+  } else if (typeof define === 'function' && define.amd) {
+    // AMD
+    define(['../../lib/codemirror'], mod);
+  } else {
+    // Plain browser env
     mod(CodeMirror);
-})(function(CodeMirror) {
-"use strict";
-
-CodeMirror.registerHelper("lint", "csslint", function(text) {
-  let found = [];
-  if (window.CSSLint) {
-
-    /* STYLISH: hack start (part 1) */
-    var rules = CSSLint.getRules();
-    var allowedRules = ["display-property-grouping", "duplicate-properties", "empty-rules", "errors", "known-properties"];
-    CSSLint.clearRules();
-    rules.forEach(function(rule) {
-      if (allowedRules.indexOf(rule.id) >= 0) {
-        CSSLint.addRule(rule);
-      }
-    });
-    /* STYLISH: hack end */
-
-    var results = CSSLint.verify(text), messages = results.messages, message = null;
-    for ( var i = 0; i < messages.length; i++) {
-      message = messages[i];
-
-      /* STYLISH: hack start (part 2) */
-      if (message.type === 'warning') {
-         // @font-face {font-family: 'Ampersand'; unicode-range: U+26;}
-        if (message.message.indexOf('unicode-range') !== -1) {
-          continue;
+  }
+})(CodeMirror => {
+  CodeMirror.registerHelper('lint', 'csslint', text => {
+    const found = [];
+    if (window.CSSLint) {
+      /* STYLISH: hack start (part 1) */
+      const rules = CSSLint.getRules();
+      const allowedRules = [
+        'display-property-grouping',
+        'duplicate-properties',
+        'empty-rules',
+        'errors',
+        'known-properties'
+      ];
+      CSSLint.clearRules();
+      rules.forEach(rule => {
+        if (allowedRules.indexOf(rule.id) >= 0) {
+          CSSLint.addRule(rule);
         }
-        else if ( // color: hsl(210, 100%, 2.2%); or color: hsla(210, 100%, 2.2%, 0.3);
-          message.message.startsWith('Expected (<color>) but found \'hsl') &&
-          /hsla?\(\s*(-?\d+)%?\s*,\s*(-?\d+)%\s*,\s*(-?\d+|-?\d*.\d+)%(\s*,\s*(-?\d+|-?\d*.\d+))?\s*\)/.test(message.message)
-        ) {
-          continue;
-        }
-        //
-      }
+      });
       /* STYLISH: hack end */
 
-      var startLine = message.line -1, endLine = message.line -1, startCol = message.col -1, endCol = message.col;
-      found.push({
-        from: CodeMirror.Pos(startLine, startCol),
-        to: CodeMirror.Pos(endLine, endCol),
-        message: message.message,
-        severity : message.type
-      });
-    }
-  }
-  return found;
-});
+      const results = CSSLint.verify(text);
+      const messages = results.messages;
+      const hslRegex = /hsla?\(\s*(-?\d+)%?\s*,\s*(-?\d+)%\s*,\s*(-?\d+|-?\d*.\d+)%(\s*,\s*(-?\d+|-?\d*.\d+))?\s*\)/;
+      let message = null;
+      for (let i = 0; i < messages.length; i++) {
+        message = messages[i];
 
-CodeMirror.registerHelper("lint", "stylelint", function(text) {
-  let found = [];
-  window.stylelint = require('stylelint').lint;
-  if (window.stylelint) {
-    return BG.chromeLocal.getValue('editorStylelintRules').then((rules = stylelintDefaultConfig.rules) => {
-      // stylelintDefaultConfig stored in stylelint-config.js & loaded by edit.html
-      if (Object.keys(rules).length === 0) {
-        rules = stylelintDefaultConfig.rules;
-      }
-      return stylelint({
-        code: text,
-        config: {
-          syntax: stylelintDefaultConfig.syntax,
-          rules: rules
-        }
-      }).then(output => {
-        const warnings = output.results.length ? output.results[0].warnings : [],
-          len = warnings.length;
-        let i, warning;
-        if (len) {
-          for (i = 0; i < len; i++) {
-            warning = warnings[i];
-            found.push({
-              from: CodeMirror.Pos(warning.line - 1, warning.column - 1),
-              to: CodeMirror.Pos(warning.line - 1, warning.column),
-              message: warning.text,
-              severity : warning.severity
-            });
+        /* STYLISH: hack start (part 2) */
+        if (message.type === 'warning') {
+           // @font-face {font-family: 'Ampersand'; unicode-range: U+26;}
+          if (message.message.indexOf('unicode-range') !== -1) {
+            continue;
+          } else if (
+            // color: hsl(210, 100%, 2.2%); or color: hsla(210, 100%, 2.2%, 0.3);
+            message.message.startsWith('Expected (<color>) but found \'hsl') &&
+            hslRegex.test(message.message)
+          ) {
+            continue;
           }
         }
-        return found;
-      });
-    });
-  }
-  return found;
-});
+        /* STYLISH: hack end */
+        const startLine = message.line - 1;
+        const endLine = message.line - 1;
+        const startCol = message.col - 1;
+        const endCol = message.col;
+        found.push({
+          from: CodeMirror.Pos(startLine, startCol),
+          to: CodeMirror.Pos(endLine, endCol),
+          message: message.message,
+          severity : message.type
+        });
+      }
+    }
+    return found;
+  });
 
+  CodeMirror.registerHelper('lint', 'stylelint', text => {
+    const found = [];
+    window.stylelint = require('stylelint').lint;
+    if (window.stylelint) {
+      return BG.chromeLocal.getValue('editorStylelintRules').then((rules = stylelintDefaultConfig.rules) => {
+        // stylelintDefaultConfig stored in stylelint-config.js & loaded by edit.html
+        if (Object.keys(rules).length === 0) {
+          rules = stylelintDefaultConfig.rules;
+        }
+        return stylelint({
+          code: text,
+          config: {
+            syntax: stylelintDefaultConfig.syntax,
+            rules: rules
+          }
+        }).then(output => {
+          const warnings = output.results.length ? output.results[0].warnings : [];
+          const len = warnings.length;
+          let warning;
+          if (len) {
+            for (let i = 0; i < len; i++) {
+              warning = warnings[i];
+              found.push({
+                from: CodeMirror.Pos(warning.line - 1, warning.column - 1),
+                to: CodeMirror.Pos(warning.line - 1, warning.column),
+                message: warning.text,
+                severity : warning.severity
+              });
+            }
+          }
+          return found;
+        });
+      });
+    }
+    return found;
+  });
 });