Add home page placeholder to not display empty page

assets/_markdown.scss

@@ -29,9 +29,7 @@ $block-border-radius: 0.15rem;
 
   code {
     font-family: 'Oxygen Mono', monospace;
-  }
 
-  p code {
     padding: 0 $padding-4;
     background: $gray-100;
     border-radius: $block-border-radius;

assets/book.scss

@@ -108,6 +108,7 @@ ul.pagination {
 
 .book-page {
   min-width: $body-min-width;
+  flex-grow: 1;
   padding: $padding-16;
 }
 
@@ -147,6 +148,7 @@ ul.pagination {
 .book-posts {
   min-width: $body-min-width;
   max-width: $sm-breakpoint;
+  flex-grow: 1;
   padding: $padding-16;
 
   article {