refactor: simpler timing inputs

src/lib/components/Button.svelte

@@ -5,7 +5,7 @@
         onclick?: (event: MouseEvent) => void;
         disabled?: boolean;
         type?: "button" | "submit" | "reset";
-        style?: "normal" | "red";
+        style?: "normal" | "red" | "invisible";
         formaction?: string;
         children?: Snippet;
     }
@@ -45,6 +45,9 @@
     .red {
         background-color: #bd4949;
     }
+    .invisible {
+        background: none;
+    }
     .button:focus {
         outline: 2px solid #007bff;
     }