Please add this CSS code you see below to your website. Here you can find an article on how to add CSS code and make it future update compatible: How to add CSS code that is future update compatible

*, 
* *,
* * *,
* * * *,
* * * * *,
* * * * *,
* * * * * *,
* * * * * * *,
* * * * * * *:before,
* * * * * * *:after,
*:hover,
* *:hover,
* * *:hover,
* * * *:hover,
* * * * *:hover,
* * * * *:hover,
* * * * * *:hover,
* * * * * * *:hover,
*:active, 
* *:active, 
* * *:active, 
* * * *:active, 
* * * * *:active, 
* * * * *:active, 
* * * * * *:active, 
* * * * * * *:active, 
*:focus, 
* *:focus, 
* * *:focus, 
* * * *:focus, 
* * * * *:focus, 
* * * * *:focus, 
* * * * * *:focus, 
* * * * * * *:focus {
border-radius:0!important;
}