diff --git a/src/components/timer.vue b/src/components/timer.vue
index ac440eb..20e6014 100644
--- a/src/components/timer.vue
+++ b/src/components/timer.vue
@@ -43,7 +43,7 @@
 </script>
 
 <template>
-	<details>
+	<details :class="{running:running}">
 		<summary><h2>Timer</h2></summary>
 		<button :disabled="running" @click="start">Start Timer</button>
 		<button :disabled="!running" @click="stop">Stop Timer</button>
@@ -77,4 +77,8 @@
 label, [type="submit"] {
 	display:block;
 }
+
+details.running {
+	background:green;
+}
 </style>