feat: block text color with stylesheet reloading

core/colours.js

@@ -83,6 +83,7 @@ Blockly.Colours = {
     "tertiary": "#FF3355"
   },
   "text": "#575E75",
+  "blockText": "#FFFFFF",
   "workspace": "#F9F9F9",
   "toolboxHover": "#4C97FF",
   "toolboxSelected": "#e9eef2",

core/css.js

@@ -76,9 +76,9 @@ Blockly.Css.mediaPath_ = '';
  * @param {string} pathToMedia Path from page to the Blockly media directory.
  */
 Blockly.Css.inject = function(hasCss, pathToMedia) {
-  // Only inject the CSS once.
+  // Clear the CSS if it has already been injected.
   if (Blockly.Css.styleSheet_) {
-    return;
+    document.head.removeChild(Blockly.Css.styleSheet_.ownerNode);
   }
   // Placeholder for cursor rule.  Must be first rule (index 0).
   var text = '.blocklyDraggable {}\n';
@@ -459,7 +459,7 @@ Blockly.Css.CONTENT = [
   '}',
 
   '.blocklyText {',
-    'fill: #fff;',
+    'fill: $colour_blockText;',
     'font-family: "Helvetica Neue", Helvetica, sans-serif;',
     'font-size: 12pt;',
     'font-weight: 500;',