views/mdc/components/expansion_panel.erb
<details id = '<%= comp.id %>' class="v-expansion mdc-elevation--z3"<% if comp.open %> open<% end %>>
<summary class="v-expansion__summary">
<% if comp.text&.text %>
<%= erb :"components/typography", :locals => {comp: comp.text, class_name: 'v-expansion__header', type: 'text', inline: comp.text&.inline} %>
<% end %>
<% if comp.secondary_text&.text %>
<%= erb :"components/typography", :locals => {comp: comp.secondary_text, class_name: 'v-expansion__secondary-content', type: 'text', inline: comp.secondary_text&.inline} %>
<% end %>
</summary>
<div class="v-expansion__content">
<%= erb :"components/render", :locals => {:components => comp.content.components, :scope=> nil} if comp.content %>
</div>
</details>