Update App.svelte

src/App.svelte

@@ -1,11 +1,72 @@
 <script>
-
+  import { onMount } from 'svelte';
+
+  let pages = [];
+  let currentPageIndex = 0;
+  let title = '';
+  let note = '';
+
+  onMount(() => {
+    const savedPages = localStorage.getItem("pages");
+    if (savedPages) {
+      pages = JSON.parse(savedPages);
+      title = pages[currentPageIndex];
+      note = localStorage.getItem(title);
+    } else {
+      addPage();
+    }
+  });
+
+  function saveNote() {
+    const storedPageName = pages[currentPageIndex];
+    if (storedPageName != title) {
+      localStorage.removeItem(storedPageName);
+      pages[currentPageIndex] = title;
+    }
+    localStorage.setItem(title, note);
+    localStorage.setItem("pages", JSON.stringify(pages));
+  }
+
+  function addPage() {
+    pages.push("New Page");
+    selectPage(pages.length ? pages.length - 1 : 0);
+  }
+
+  function selectPage(index) {
+    currentPageIndex = index;
+    title = pages[currentPageIndex];
+    note = localStorage.getItem(title);
+  }
 </script>
 
-<main>
-  Hello World
+<aside class="fixed top-0 left-0 z-40 w-60 h-screen">
+<div class="bg-light-gray overflow-y-auto py-5 px-3 h-full border-r border-gray-200">
+  <ul class="space-y-2">
+    {#each pages as page, index}
+    <li>
+        <button on:click={()=>selectPage(index)} class="{index == currentPageIndex ? 'bg-dark-gray' : ''} py-2 px-3 text-gray-900 rounded-lg">{page}</button>
+    </li>
+    {/each}
+    <li class="text-center"><button on:click={addPage} class="font-medium">+ Add page</button></li>
+  </ul>
+</div>
+</aside>
+
+<main class="p-4 ml-60 h-auto">
+  <div class="grid grid-cols-2 items-center mb-3">
+    <h1 class="text-3xl font-bold" contenteditable bind:textContent={title}></h1>
+    <button class="ml-auto bg-gray-800 text-white px-5 py-2.5 rounded-lg font-medium text-sm mt-3 hover:bg-gray-900" on:click={saveNote}>Save</button>
+  </div>
+  <hr/>
+  <textarea class="mt-3 block w-full bg-gray-50 border border-gray-300 rounded-lg text-gray-900 p-2.5" bind:value={note}></textarea>
 </main>
 
 <style>
+.bg-light-gray {
+  background: #FBFBFB;
+}
 
+.bg-dark-gray {
+  background: #EFEFEF;
+}
 </style>