Remove Roboto from partner-style.css, improve button styling

Signed-off-by: Celeste Horgan <celeste@cncf.io>

assets/scss/_base.scss

@@ -71,6 +71,7 @@ footer {
     background-color: $blue;
     text-decoration: none;
     font-size: 1rem;
+    border: 0px;
   }
 
   #cellophane {

content/en/includes/partner-style.css

@@ -82,7 +82,6 @@
 .button{
   max-width: 100%;
 	box-sizing: border-box;
-	font-family: "Roboto", sans-serif;
 	margin: 0;
 	display: inline-block;
 	border-radius: 6px;