Images scale to fit width of instructions panel (#1593)

* issue #1573 fixed -- images instructions scale to fit width of instructions panel

* postcss-cssnext dependency removed - updated postcsspresetenv config to handle nesting rules

* uninstalled postcss-cssnext dependency

* package-lock.json reset

* npm installed to update package-lock.json

* Revert package-lock.json to master

No changes to dependencies here, so no reason package-lock should change

Author: Eric Snell

gulpfile.js

@@ -52,7 +52,14 @@ gulp.task(
 );
 
 gulp.task('css', () => {
-  const processors = [postcssPresetEnv({browsers: postcssBrowsers})];
+  const processors = [
+    postcssPresetEnv({
+      features: {
+        'nesting-rules': true,
+      },
+      browsers: postcssBrowsers,
+    }),
+  ];
   if (process.env.NODE_ENV === 'production') {
     processors.push(cssnano());
   }