Make the hr on markdown pages slightly less weird

src/components/Markdown.astro

···
     height: 5px;
     border: none;
     border-image: var(--hr-png) 0 5 fill / 0 5px round;
-    width: clamp(60ch, 80vw, 120ch);
+    width: clamp(60ch, 80vw, 80ch);
     margin-inline: auto;
 
     @media (max-width: 60ch) {
-      width: 100%;
+      width: calc(100% - 20px);
+      margin-inline: 10px;
     }
   }
 </style>