Change btn-used default and hovered colors for clarity

tildes/scss/modules/_btn.scss

@@ -33,13 +33,14 @@
 }
 
 .btn-used {
-  border-color: darken($violet, 3%);
-  color: $violet;
-
-  &:hover {
   background-color: darken($violet, 3%);
   border-color: darken($violet, 8%);
   color: #fff;
+
+  &:hover {
+    background-color: darken($blue, 3%);
+    border-color: darken($blue, 8%);
+    color: #fff;
   }
 }