fix minor mobile UI issues

app/views/mfa_setup/_form.html.erb

@@ -3,7 +3,7 @@
     Use an authenticator mobile app like Google Authenticator or 1Password to scan the QR code below.
   </p>
   <div>
-    <%== RQRCode::QRCode.new(@provision_url).as_svg(viewbox: true, svg_attributes: { class: 'w-80 h-80 my-4 mx-auto' }) %>
+    <%== RQRCode::QRCode.new(@provision_url).as_svg(viewbox: true, svg_attributes: { class: 'md:w-80 md:h-80 my-4 mx-auto' }) %>
   </div>
   <div class="form-control my-6 space-y-2">
     <%= f.text_field :otp_attempt, required: true, placeholder: 'XXX-XXX', class: 'base-input text-center' %>