Fix gap issue

assets/css/main.css

@@ -13,6 +13,7 @@
 html {
   display: flex;
   justify-content: center;
+  padding: 1rem;
 }
 
 body {
@@ -21,7 +22,7 @@ body {
   font-family: 'Noto Sans';
   line-height: 1.5;
   text-align: justify;
-  margin: 1rem;
+  margin: 0;
   width: 100%;
   max-width: 768px;
 }
@@ -72,6 +73,7 @@ code { font-family: 'IBM Plex Mono', monospace; }
 div.highlight pre {
   padding: 0.5rem;
   border-radius: 0.5rem;
+  overflow: auto;
 }
 
 /* Tables */