added smooth scroll behavior using css

Author: Jisan-mia

src/components/layout/app.css

@@ -12,6 +12,8 @@
 html {
   -ms-text-size-adjust: 100%;
   -webkit-text-size-adjust: 100%;
+  scroll-behavior: smooth;
+  scroll-padding-top: 1em;
 }
 
 body {