:beetle: Prevent main image overflow on tiny screens

src/templates/main.html

@@ -94,9 +94,9 @@ $if(title)$
             <header id="title-block-header" class="focus-center">
                 <h1 class="title">$title$</h1>
 $if(img.main)$
-                <img class="rounded" src="$img.main.path$"$if(img.main.alt)$ alt="$img.main.alt$"$endif$>
+                <img class="img-fluid rounded" src="$img.main.path$"$if(img.main.alt)$ alt="$img.main.alt$"$endif$>
 $elseif(img.icon)$
-                <img class="rounded" src="$img.icon.path$"$if(img.icon.alt)$ alt="$img.icon.alt$"$endif$>
+                <img class="img-fluid rounded" src="$img.icon.path$"$if(img.icon.alt)$ alt="$img.icon.alt$"$endif$>
 $endif$
 $if(subtitle)$
                 <h2 class="subtitle">$subtitle$</h2>