revert base folder structure to src/*

src/renderer/utils/cssVar.ts

@@ -0,0 +1,17 @@
+// Helper for getting/setting css-variables
+
+export function cssVar(elem: HTMLElement) {
+  return {
+    get(name: string) {
+      const value = window.getComputedStyle(elem).getPropertyValue(name).trim();
+      return {
+        toString: () => value,
+        valueOf: () => parseFloat(value)
+      };
+    },
+    set(name: string, value: number | string) {
+      if (typeof value === "number") value = value + "px";
+      elem.style.setProperty(name, value);
+    }
+  }
+}