FEAT: #36 Added in Collapsible.svelte re-usable component.

src/lib/components/Collapsible.svelte

@@ -0,0 +1,33 @@
+<script lang="ts">
+    export let open = false;
+</script>
+
+<div class="w-full">
+    <button
+        type="button"
+        class="flex items-center justify-between w-full px-2 py-2 text-left rounded hover:font-bold transition group"
+        on:click={() => open = !open}
+        aria-expanded={open}
+    >
+        <span><slot name="label"/></span>
+        <svg
+            class="w-5 h-5 ml-2 transition-transform duration-200"
+            style="transform: rotate({open ? 90 : 0}deg)"
+            fill="none"
+            stroke="currentColor"
+            stroke-width="2"
+            viewBox="0 0 24 24"
+        >
+            <path stroke-linecap="round" stroke-linejoin="round" d="M9 5l7 7-7 7" />
+        </svg>
+    </button>
+    <div
+        class="overflow-hidden transition-all duration-300"
+        style="max-height: {open ? '1000px' : '0'}"
+        aria-hidden={!open}
+    >
+        <div class="pt-2">
+            <slot name="content"/>
+        </div>
+    </div>
+</div>