Collapse sidebar navigation list on smaller screens

- CSS only solution using "check-box hack"
- Add new UI text label `menu_label` in _data/ui-text.yml
- Close #607

_data/ui-text.yml

@@ -8,6 +8,7 @@ en: &DEFAULT_EN
   pagination_next            : "Next"
   breadcrumb_home_label      : "Home"
   breadcrumb_separator       : "/"
+  menu_label                 : "Toggle Menu"
   toc_label                  : "On This Page"
   ext_link_label             : "Direct Link"
   less_than                  : "less than"
@@ -56,6 +57,7 @@ es: &DEFAULT_ES
   pagination_next            : "Siguiente"
   breadcrumb_home_label      : "Inicio"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Contenidos"
   ext_link_label             : "Enlace"
   less_than                  : "menos de"
@@ -100,6 +102,7 @@ fr: &DEFAULT_FR
   pagination_next            : "Suivant"
   breadcrumb_home_label      : "Accueil"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Sur cette page"
   ext_link_label             : "Lien direct"
   less_than                  : "plus petit que"
@@ -147,6 +150,7 @@ tr: &DEFAULT_TR
   pagination_next            : "Sonraki"
   breadcrumb_home_label      : "Ana Sayfa"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "İçindekiler"
   ext_link_label             : "Doğrudan Bağlantı"
   less_than                  : "Şu süreden az: "
@@ -189,6 +193,7 @@ pt: &DEFAULT_PT
   pagination_next            : "Seguinte"
   breadcrumb_home_label      : "Início"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Nesta Página"
   ext_link_label             : "Link Direto"
   less_than                  : "menos de"
@@ -227,6 +232,7 @@ pt-BR:
   pagination_next            : "Próxima"
   breadcrumb_home_label      : "Home"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Nesta página"
   ext_link_label             : "Link direto"
   less_than                  : "meno que"
@@ -269,6 +275,7 @@ it: &DEFAULT_IT
   pagination_next            : "Prossima"
   breadcrumb_home_label      : "Home"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Indice della pagina"
   ext_link_label             : "Link"
   less_than                  : "meno di"
@@ -311,6 +318,7 @@ zh: &DEFAULT_ZH
   pagination_next            : "向后"
   breadcrumb_home_label      : "首页"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "在本页上"
   ext_link_label             : "直接链接"
   less_than                  : "少于"
@@ -359,6 +367,7 @@ de: &DEFAULT_DE
   pagination_next            : "Nächste"
   breadcrumb_home_label      : "Home"
   breadcrumb_separator       : "/"
+  menu_label                 :
   toc_label                  : "Auf dieser Seite"
   ext_link_label             : "Direkter Link"
   less_than                  : "weniger als"

_includes/nav_list

@@ -1,8 +1,10 @@
 {% assign navigation = site.data.navigation[include.nav] %}
 
 <nav class="nav__list">
-  {% if page.sidebar.title %}<header><h4 class="nav__title" style="padding: 0;">{{ page.sidebar.title }}</h4></header>{% endif %}
-  <ul>
+  {% if page.sidebar.title %}<h3 class="nav__title" style="padding-left: 0;">{{ page.sidebar.title }}</h3>{% endif %}
+  <input id="ac-toc" name="accordion-toc" type="checkbox" />
+  <label for="ac-toc">{{ site.data.ui-text[site.locale].menu_label | default: "Toggle Menu" }}</label>
+  <ul class="nav__items">
     {% for nav in navigation %}
       <li>
         {% if nav.url %}

_sass/_base.scss

@@ -290,6 +290,8 @@ nav {
   }
 
   a {
+    display: block;
+    padding-bottom: 0.25em;
     text-decoration: none;
   }
 

_sass/_navigation.scss

@@ -314,7 +314,39 @@
    ========================================================================== */
 
 .nav__list {
-  font-size: 1.25rem;
+  margin: 2em 0 1.5em 0;
+
+  input[type="checkbox"],
+  label {
+    display: none;
+  }
+
+  @include breakpoint(max-width $large) {
+
+    label {
+      position: relative;
+      display: inline-block;
+      padding: 0.5em 1em;
+      font-size: $type-size-6;
+      border: 1px solid $light-gray;
+      border-radius: $border-radius;
+      z-index: 20;
+      -webkit-transition: 0.2s ease-out;
+      transition: 0.2s ease-out;
+      cursor: pointer;
+
+      &:hover {
+        color: #fff;
+        border-color: $gray;
+        background-color: mix(white, #000, 20%);
+      }
+    }
+
+    /* selected*/
+    input:checked + label {
+      color: white;
+      background-color: mix(white, #000, 20%);
+    }
 
     ul {
       margin-bottom: 1em;
@@ -323,12 +355,12 @@
     a {
       display: block;
       padding: 0.125em 0;
-    color: inherit;
 
       &:hover {
         text-decoration: underline;
       }
     }
+  }
 
   .active {
     margin-left: -0.5em;
@@ -345,6 +377,37 @@
   }
 }
 
+.nav__list .nav__items {
+  margin: 0;
+  font-size: 1.25rem;
+
+  @include breakpoint(max-width $large) {
+    position: relative;
+    max-height: 0;
+    opacity: 0;
+    overflow: hidden;
+    z-index: 10;
+    -webkit-transition: 0.3s ease-in-out;
+    transition: 0.3s ease-in-out;
+    -webkit-transform: translate(0, 10%);
+        -ms-transform: translate(0, 10%);
+            transform: translate(0, 10%);
+  }
+}
+
+@include breakpoint(max-width $large) {
+  .nav__list input:checked ~ .nav__items {
+    -webkit-transition: 0.5s ease-in-out;
+    transition: 0.5s ease-in-out;
+    max-height: 100vh;
+    opacity: 1;
+    margin-top: 1em;
+    -webkit-transform: translate(0, 0);
+        -ms-transform: translate(0, 0);
+            transform: translate(0, 0);
+  }
+}
+
 .nav__title {
   margin: 0;
   padding: 0.5rem 1rem;

_sass/_sidebar.scss

@@ -33,10 +33,6 @@
     font-family: $sans-serif-narrow;
   }
 
-  h3, h4 {
-    font-size: $type-size-5;
-  }
-
   p, li {
     font-family: $sans-serif;
     font-size: $type-size-6;