Make Add/Update clip buttons green to bring more attention to it

src/components/Preview.vue

@@ -77,7 +77,7 @@
 
     <!-- Add Clip button -->
     <div class="timeline-button timeline-button-right">
-      <button :title="actionButtonTitle" type="button" class="btn btn-primary timeline-btn d-flex flex-column justify-content-center align-items-center" @click="createClipBtn">
+      <button :title="actionButtonTitle" type="button" class="btn btn-success timeline-btn d-flex flex-column justify-content-center align-items-center" @click="createClipBtn">
         <svg v-if="!isEditingClip" xmlns="http://www.w3.org/2000/svg" width="25" height="25" fill="currentColor" class="bi bi-plus" viewBox="0 0 16 16">
           <path d="M8 4a.5.5 0 0 1 .5.5v3h3a.5.5 0 0 1 0 1h-3v3a.5.5 0 0 1-1 0v-3h-3a.5.5 0 0 1 0-1h3v-3A.5.5 0 0 1 8 4z"/>
         </svg>