add color picker

js/sudoku.js

@@ -172,6 +172,9 @@ function oninput() {
         this.previousPlaceholder = this.placeholder
         refreshBox(this)
     }
+    if (penColor) {
+        this.style.setProperty("color", penColor)
+    }
 }
 
 function refreshBox(box) {
@@ -321,6 +324,12 @@ function insert(radio) {
     }
 }
 
+let penColor
+
+function changeColor() {
+    penColor = colorPicker.value
+}
+
 function undo() {
     if (history.length) {
         const previousState = history.pop()