Add hover effect to flat buttons

src/scss/_buttons.scss

@@ -1,7 +1,16 @@
 a.raised-button {
+  $hover-transition-duration: 0.4s;
+
   padding: 7px 35px;
   background-color: $primary;
+  font-family: Montserrat, sans-serif;
   color: white;
-  border: solid 1px;
   border-radius: 30px;
+  transition: $hover-transition-duration;
+
+  &:hover {
+    background-color: $primary-dark;
+    transition: $hover-transition-duration;
+    text-decoration: none;
+  }
 }