Increase menu button touch area on small screens

Some users might not be able to touch the icon due to a motor
disability. Other users might think the "Menu" text is part of the
button and try to touch it instead.

Making the "Menu" text part of the button makes it easier to show/hide
this menu. Besides, it lets screen reader users with a small screen hear
the word "Menu" associated to the button.

We could simplify the HTML a bit more but Foundation's `hamburger` mixin
uses the `::after` element with `position: absolute`, so we can't apply
it directly to the button without making the CSS more complex.

app/assets/stylesheets/layout.scss

@@ -667,9 +667,12 @@ body > header,
   }
 }
 
+.menu-button {
+  color: inherit;
+}
+
 .menu-icon {
   @include hamburger($color: currentcolor, $color-hover: currentcolor);
-  color: inherit;
 }
 
 .title-bar {

app/views/layouts/_admin_header.html.erb

@@ -11,8 +11,10 @@
 
   <div class="expanded row admin-top-bar">
     <div class="title-bar" data-responsive-toggle="responsive_menu" data-hide-for="medium">
-      <button class="menu-icon" type="button" data-toggle="responsive_menu"></button>
+      <button class="menu-button" type="button" data-toggle="responsive_menu">
-      <div class="title-bar-title"><%= t("application.menu") %></div>
+        <span class="menu-icon"></span>
+        <span class="title-bar-title"><%= t("application.menu") %></span>
+      </button>
     </div>
 
     <div class="top-bar">

app/views/layouts/_header.html.erb

@@ -16,8 +16,10 @@
     <div class="top-bar">
 
       <span data-responsive-toggle="responsive-menu" data-hide-for="medium" class="float-right">
-        <button type="button" class="menu-icon" data-toggle></button>
+        <button type="button" class="menu-button" data-toggle>
+          <span class="menu-icon"></span>
           <%= t("application.menu") %>
+        </button>
       </span>
 
       <h1 class="top-bar-title">

spec/system/admin_spec.rb

@@ -104,4 +104,22 @@ describe "Admin" do
       expect(page).to have_link "Participatory budgets"
     end
   end
+
+  describe "Menu button", :admin do
+    scenario "is not present on large screens" do
+      visit admin_root_path
+
+      expect(page).not_to have_button "Menu"
+    end
+
+    scenario "toggles the menu on small screens", :small_window do
+      visit admin_root_path
+
+      expect(page).not_to have_link "My account"
+
+      click_button "Menu"
+
+      expect(page).to have_link "My account"
+    end
+  end
 end

spec/system/home_spec.rb

@@ -138,6 +138,24 @@ describe "Home" do
     end
   end
 
+  describe "Menu button" do
+    scenario "is not present on large screens" do
+      visit root_path
+
+      expect(page).not_to have_button "Menu"
+    end
+
+    scenario "toggles the menu on small screens", :small_window do
+      visit root_path
+
+      expect(page).not_to have_link "Sign in"
+
+      click_button "Menu"
+
+      expect(page).to have_link "Sign in"
+    end
+  end
+
   scenario "if there are cards, the 'featured' title will render" do
     create(:widget_card,
       title: "Card text",