mas ajuste del boton

app/pages/compras.php

@@ -37,9 +37,11 @@ $imagenes = [
             <div style="width: 300px; height: 100px; background-color: <?php echo $_GET["color"] ?>;"></div>
         </div>
     </div>
-    <button class="btn btn-primary mt-5 w-25">
-        Comprar
-    </button>
+    <div class="text-center d-flex flex-column align-items-center">
+        <button class="btn btn-primary mt-5 w-25">
+            Comprar
+        </button>
+    </div>
 </article>