feature：代码初始化。

src/rem.js

@@ -0,0 +1,20 @@
+/*
+ * @Description:
+ * @Version: 1.0.0
+ * @Author: fujingwen
+ * @Date: 2023-02-17 10:10:24
+ * @FilePath: /RuoYi-Cloud-Vue3/src/rem.js
+ */
+;(function (doc, win) {
+  const docEl = doc.documentElement
+  const resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize'
+  const recalc = function () {
+    const clientWidth = docEl.clientWidth
+    if (!clientWidth) return
+    docEl.style.fontSize = clientWidth / 19.2 + 'px'
+  }
+  if (!doc.addEventListener) return
+  recalc()
+  win.addEventListener(resizeEvt, recalc, false)
+  doc.addEventListener('DOMContentLoaded', recalc, false)
+})(document, window)