fix: Add conditional border-radius styling to template

Introduces a style block that reverts border-radius for specific elements when USE_ROUNDED_CORNERS is not set. This allows dynamic control of rounded corners based on configuration.

templates/root.html

@@ -23,6 +23,14 @@
 
         {% include "config/index.html" %}
 
+        {% if not USE_ROUNDED_CORNERS %}
+        <style>
+            .viewer-container .player-container, .item-thumb, a.item-thumb {
+                border-radius: revert !important;
+            }
+        </style>
+        {% endif %}
+
     {% endblock head %}
 
 </head>