Update account layout styling and responsiveness

- Updated the container class to remove horizontal margin and added left and right margin for smaller screens
- Centered the heading text within the container
- Adjusted the card width to be full-width on mobile devices and 3/12 of the screen width on larger screens

src/routes/account/+layout.svelte

@@ -1,5 +1,5 @@
-<div class="container h-full mx-auto flex justify-center items-center flex-col">
-    <h1 class="my-3 h1">Blackbird Chess</h1>
+<div class="h-full mx-4 md:mx-auto flex justify-center items-center flex-col">
+    <h1 class="my-3 h1 text-center">Blackbird Chess</h1>
 
     {#if typeof globalvars.user == 'undefined' }
         {#each alertsvar as alert, i}
@@ -15,7 +15,7 @@
             </aside>
         {/each}
     {/if}
-    <div class="card variant-ringed p-4 w-50 text-token space-y-4">
+    <div class="card variant-ringed p-4 m-4 w-full md:w-3/12 text-token">
         <slot />
     </div>