Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/autoprefixer/lib/hacks/cross-fade.js

@@ -0,0 +1,35 @@
+let list = require('postcss').list
+
+let Value = require('../value')
+
+class CrossFade extends Value {
+  replace(string, prefix) {
+    return list
+      .space(string)
+      .map(value => {
+        if (value.slice(0, +this.name.length + 1) !== this.name + '(') {
+          return value
+        }
+
+        let close = value.lastIndexOf(')')
+        let after = value.slice(close + 1)
+        let args = value.slice(this.name.length + 1, close)
+
+        if (prefix === '-webkit-') {
+          let match = args.match(/\d*.?\d+%?/)
+          if (match) {
+            args = args.slice(match[0].length).trim()
+            args += `, ${match[0]}`
+          } else {
+            args += ', 0.5'
+          }
+        }
+        return prefix + this.name + '(' + args + ')' + after
+      })
+      .join(' ')
+  }
+}
+
+CrossFade.names = ['cross-fade']
+
+module.exports = CrossFade