Sass warning fixes

src/assets/demo/demo.scss

@@ -1,2 +1,2 @@
+@use './code.scss';
 @import './flags/flags.css';
-@import './code.scss';

src/assets/layout/_menu.scss

@@ -1,3 +1,5 @@
+@use 'mixins' as *;
+
 .layout-sidebar {
     position: fixed;
     width: 20rem;

src/assets/layout/_topbar.scss

@@ -1,3 +1,5 @@
+@use 'mixins' as *;
+
 .layout-topbar {
     position: fixed;
     height: 4rem;

src/assets/layout/layout.scss

@@ -1,13 +1,13 @@
-@import './variables/_common';
-@import './variables/_light';
-@import './variables/_dark';
-@import './_mixins';
-@import './_preloading';
-@import './_core';
-@import './_main';
-@import './_topbar';
-@import './_menu';
-@import './_footer';
-@import './_responsive';
-@import './_utils';
-@import './_typography';
+@use './variables/_common';
+@use './variables/_light';
+@use './variables/_dark';
+@use './_mixins';
+@use './_preloading';
+@use './_core';
+@use './_main';
+@use './_topbar';
+@use './_menu';
+@use './_footer';
+@use './_responsive';
+@use './_utils';
+@use './_typography';

src/assets/styles.scss

@@ -1,5 +1,5 @@
 /* You can add global styles to this file, and also import other style files */
-@import '@/assets/layout/layout.scss';
-@import 'primeicons/primeicons.css';
-@import '@/assets/demo/demo.scss';
+@use '@/assets/layout/layout.scss';
+@use 'primeicons/primeicons.css';
+@use '@/assets/demo/demo.scss';