message: feat(frontend): viewer help styling
diff: <template>
  <v-card>
  <div>
  - <v-expansion-panels>
  + <v-expansion-panels v-model="panel" accordion>
  <v-expansion-panel>
  <v-expansion-panel-header>Rotation</v-expansion-panel-header>
  - <v-expansion-panel-content>
  + <v-expansion-panel-content class="caption">
  Simply click and drag with your left mouse button.
  - <v-img src="@/assets/rotating.gif" max-height="350" contain />
  + <v-img class="mt-4" src="@/assets/rotating.gif" max-height="350" contain />
  </v-expansion-panel-content>
  </v-expansion-panel>
  <v-expansion-panel>
  <v-expansion-panel-header>Panning</v-expansion-panel-header>
  - <v-expansion-panel-content>
  + <v-expansion-panel-content class="caption">
  Simply click and drag with your right mouse button.
  - <v-img src="@/assets/panning.gif" max-height="350" contain />
  + <v-img class="mt-4" src="@/assets/panning.gif" max-height="350" contain />
  </v-expansion-panel-content>
  </v-expansion-panel>
  <v-expansion-panel>
  <v-expansion-panel-header>Zooming</v-expansion-panel-header>
  - <v-expansion-panel-content>
  + <v-expansion-panel-content class="caption">
  Double click on an object to zoom to it.
  <br />
  Double click anywhere else to zoom to the entire scene.
  <br />
  Use your mouse's scroll wheel to zooom in and out.
  - <v-img src="@/assets/zooming.gif" max-height="350" contain />
  + <v-img class="mt-4" src="@/assets/zooming.gif" max-height="350" contain />
  </v-expansion-panel-content>
  </v-expansion-panel>
  <v-expansion-panel>
  <v-expansion-panel-header>Sections</v-expansion-panel-header>
  - <v-expansion-panel-content>
  + <v-expansion-panel-content class="caption">
  The section box can be moved around as a whole. You can also move individual
  faces of the section box by clicking on them.
  - <v-img src="@/assets/sectionbox.gif" max-height="350" contain />
  + <v-img
  + class="mt-4"
  + src="@/assets/sectionbox.gif"
  + max-height="350"
  + contain
  + />
  </v-expansion-panel-content>
  </v-expansion-panel>
  </v-expansion-panels>
  </v-card>
  </template>
  <script>
  -export default {}
  +export default {
  + data() {
  + return {
  + panel: 0
  + }
  + }
  +}
  </script>
  