fix: make is-land elements display block for proper widget spacing

The <is-land> custom element defaults to display:inline, which breaks
margin spacing between adjacent widgets. Setting it to block ensures
widgets wrapped in is-land (blogroll, social-activity, github, etc.)
get proper mb-4 spacing from the .widget class.

css/tailwind.css

@@ -278,6 +278,11 @@
     @apply inline-block px-3 py-1 text-sm bg-surface-100 dark:bg-surface-800 rounded-full;
   }
 
+  /* Ensure is-land custom elements don't break block layout flow */
+  is-land {
+    @apply block;
+  }
+
   /* Widget cards */
   .widget {
     @apply p-4 mb-4 bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden;