Tabs on term_table page, for navigating between houses

Makes it easier to move from, for example, a country\u2019s lower to
upper chamber. Will also help people navigate once executive
branch is included (#13297).

views/sass/_components.scss

@@ -498,12 +498,43 @@ p.lead {
 
 // Little round social icons for membership tables
 .person-link {
-  display: inline-block;
-  width: 24px;
-  padding-top: 24px;
-  height: 0;
-  overflow: hidden;
-  vertical-align: middle;
-  border-radius: 100%;
-  margin-right: 0.3em;
+    display: inline-block;
+    width: 24px;
+    padding-top: 24px;
+    height: 0;
+    overflow: hidden;
+    vertical-align: middle;
+    border-radius: 100%;
+    margin-right: 0.3em;
+}
+
+.house-tabs {
+    @extend .unstyled-list;
+    @extend .inline-list;
+    padding-top: 1em;
+
+    @media (min-width: $medium_screen) and (min-height: 600px) {
+        padding-top: 1.5em;
+    }
+}
+
+.house-tab {
+    display: inline-block;
+    padding: 0.5em 1em;
+    border-radius: 5px 5px 0 0;
+    background-color: mix($colour_green, #fff, 25%);
+    background: linear-gradient(180deg, mix($colour_green, #fff, 20%), 50%, mix($colour_green, #fff, 30%));
+    color: darken($colour_green, 10%) !important;
+
+    &:hover,
+    &:focus {
+        background-color: mix($colour_green, #fff, 15%);
+        background: linear-gradient(180deg, mix($colour_green, #fff, 10%), 50%, mix($colour_green, #fff, 20%));
+    }
+}
+
+.house-tab--active,
+.house-tab--active:hover,
+.house-tab--active:focus {
+background: #fff;
 }

views/term_table.erb

@@ -1,3 +1,19 @@
+<div class="page-section page-section--green page-section--no-padding">
+    <div class="container text-center">
+        <ul class="house-tabs">
+          <% @page.country.legislatures.each do |house| %>
+            <li>
+                <a
+                  class="house-tab <% if @page.house == house %>house-tab--active<% end %>"
+                  href="<%= term_table_url(house.legislative_periods.first) %>">
+                    <%= house.name %>
+                </a>
+            </li>
+          <% end %>
+        </ul>
+    </div>
+</div>
+
 <div class="page-section" id="term">
     <div class="container text-center">
         <h1><span class="avatar"><i class="fa fa-university"></i></span> <%= @page.current_term.name %></h1>