Düzeltme yapıldı.

assets/main.css

@@ -50,6 +50,7 @@ body {
     background-image: linear-gradient(to bottom, #416e75, #529290, #6db7a6, #94dbb5, #c6ffc1);
 }
 
+
 button {
     position: relative;
     display: inline-block;

main.html

@@ -6,6 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Mangala | CLUTCH</title>
     <link rel="stylesheet" href="assets/main.css" />
+
     <link rel="stylesheet" href="assets/bootstrap.min.css" />
 </head>