diff --git a/index.html b/index.html
index 31a8e075..82308fce 100644
--- a/index.html
+++ b/index.html
@@ -11,10 +11,10 @@
     {% if jekyll.environment == "development" %}{% include dev-info.html %}{% endif %}
     {% include topnav.html search=false %}
     <section class="container mb-5">
-        <div class="card border border-primary text-primary text-center">
+        <div class="card border bg-primary text-white text-center">
             <div class="card-body">
                 <h5 class="card-title fs-3">THIS IS A SANDBOX</h5>
-                <p class="card-text">If you want to access the Infectious Diseases Toolkit, please go to <a href="https://www.infectious-diseases-toolkit.org/">Infectious Diseases Toolkit</a>. This is a sandbox for experimenting. Its content can be meaningless and gets periodically modified and deleted without warning.</p>
+                <p class="card-text">If you want to access the Infectious Diseases Toolkit, please go to <a class="link-body-emphasis" href="https://www.infectious-diseases-toolkit.org/">Infectious Diseases Toolkit</a>. This is a sandbox for experimenting. Its content can be meaningless and gets periodically modified and deleted without warning.</p>
             </div>
         </div>
     </section>