fix: add style to button and remove unused css (sveltejs#383)

Author: JabSYsEmb

content/tutorial/03-sveltekit/06-forms/04-progressive-enhancement/app-b/src/routes/+page.svelte

@@ -56,7 +56,14 @@
 		flex: 1;
 	}
 
-	.saving {
+	button {
+		border: none;
+		background: url(./remove.svg) no-repeat 50% 50%;
+		background-size: 1rem 1rem;
+		cursor: pointer;
+		height: 100%;
+		aspect-ratio: 1;
 		opacity: 0.5;
+		transition: opacity 0.2s;
 	}
 </style>