General source code refactoring

src/content/styles.js

@@ -0,0 +1,20 @@
+function createContentStyles({
+  STYLE_ID,
+  redwoodStyles,
+  environment
+}) {
+  const { document } = environment;
+  function ensureExtensionStyles() {
+    if (document.getElementById(STYLE_ID)) {
+      return;
+    }
+
+    const style = document.createElement("style");
+    style.id = STYLE_ID;
+    style.textContent = redwoodStyles;
+
+    document.head.append(style);
+  }
+
+  return { ensureExtensionStyles };
+}