Update index.html

Author: asadgulxar10

index.html

@@ -65,7 +65,7 @@
 	<div class="container">
 		<h1><a style="text-decoration: none; color: #f1c40f; margin-left: 0.25rem;" href="" onclick="location.reload();">CALCULATOR</a></h1 >
 		<div class="calculator">
-			<input type="text" name="screen" id="answer">
+			<input type="text" name="screen" id="answer" readonly>
 			<table>
 				<tr>
 					<td><button>(</button></td>