Small css color updates.

unit-conversion/src/features/card/card.css

@@ -2,7 +2,7 @@
   display: flex;
   justify-content: space-around;
   align-items: center;
-  margin: 20px;
+  margin: 7%;
   min-height: 20%;
   border-radius: 10px;
   background-color: rgba(255 255 255 / 90%);