Refactored some things in the frontend

- use button insted of inputfield
- make use of conditional rendering

frontend/src/components/Button.css

@@ -31,6 +31,12 @@
   font-size: 1.3em;
 }
 
+.btn--full{
+  padding: 12px 26px;
+  margin: 0 auto;
+  font-size: 1.5em;
+}
+
 .btn--large:hover,
 .btn--medium:hover {
   transition: all 0.3s ease-out;
@@ -38,3 +44,4 @@
   color: var(--secondary);
   transition: 250ms;
 }
+