Fix broken card in demo
Fix broken card in demo

tipunch74/MaterialDesignInXamlToolkit,tipunch74/MaterialDesignInXamlToolkit,ButchersBoy/MaterialDesignInXamlToolkit,ButchersBoy/MaterialDesignInXamlToolkit,ButchersBoy/MaterialDesignInXamlToolkit,DingpingZhang/MaterialDesignInXamlToolkit,tipunch74/MaterialDesignInXamlToolkit