Не работает border-radius

@import url('https://fonts.googleapis.com/css?family=Fira+Sans+Condensed:300,400,500,700'); 
a.logo { 
  font-family: 'Fira Sans Condensed', sans-serif; 
  font-weight: 400; 
  font-size: 25px; 
} 
 
.logo { 
  padding: 6px 20px 5px; 
  margin-top: 0.65em; 
  border: 0.115em solid transparent; 
  display: inline-block; 
   
  /* border */ 
  -moz-border-image: -moz-linear-gradient(90deg, rgba(179, 0, 255, 0.9556197478991597) 30%, rgba(42, 198, 231, 1) 100%); 
  -webkit-border-image: -webkit-linear-gradient(90deg, rgba(179, 0, 255, 0.9556197478991597) 30%, rgba(42, 198, 231, 1) 100%); 
  border-image: linear-gradient(90deg, rgba(179, 0, 255, 0.9556197478991597) 30%, rgba(42, 198, 231, 1) 100%); 
  border-image-slice: 1; 
  -webkit-border-radius: 20px; 
  -moz-border-radius: 20px; 
  border-radius: 20px; 
   
  /* text */ 
  background: -webkit-linear-gradient(360deg, rgba(179, 0, 255, 0.9556197478991597) 30%, rgba(42, 198, 231, 1) 100%); 
  -webkit-background-clip: text; 
  -webkit-text-fill-color: transparent; 
}

<a class="logo">ЛОГОТИП</a>