Link to homepage should use internal Gatsby router

src/components/Layout/Header.js

@@ -26,6 +26,9 @@ const useStyles = makeStyles(theme => ({
       marginRight: theme.spacing(1),
     },
   },
+  link: {
+    width: "100%",
+  },
 }));
 
 function Header({ twhelpUrl, lang, languages, pathname }) {
@@ -89,9 +92,10 @@ function Header({ twhelpUrl, lang, languages, pathname }) {
                     title="Home"
                     color="inherit"
                     underline="none"
-                    href={routes[lang].HOME}
+                    className={classes.link}
+                    to={routes[lang].HOME}
                   >
-                    Home
+                    Homepage
                   </Link>
                 </MenuItem>
                 <MenuItem>

src/pages/404.js

@@ -13,6 +13,9 @@ const useStyles = makeStyles(() => ({
     justifyContent: "center",
     textAlign: "center",
   },
+  layout: {
+    minHeight: "100vh",
+  },
 }));
 
 const NotFoundPage = ({ location, pageContext }) => {
@@ -22,6 +25,7 @@ const NotFoundPage = ({ location, pageContext }) => {
     <Layout
       showHeader={false}
       showFooter={false}
+      className={classes.layout}
       lang={pageContext.langKey}
       pathname={location.pathname}
     >