feat: implement post search using Pagefind (#12)

src/components/GlobalStyles.astro

@@ -195,5 +195,15 @@ color_set({
     .float-panel.closed {
         @apply top-[4.75rem] opacity-0 pointer-events-none
     }
+    .search-panel mark {
+        @apply bg-transparent text-[var(--primary)]
+    }
+
+    .text-deep {
+        @apply text-black/90 dark:text-white/90
+    }
+    .text-sub {
+        @apply text-black/50 dark:text-white/50
+    }
 }
 </style>