[fix] wrap categories on small screens ++ some code formatting - closes #647

searx/static/themes/oscar/less/logicodev/advanced.less

 #advanced-search-container {
-    display:none;
-    text-align:left;
-    margin-bottom:1rem;
+    display: none;
+    text-align: left;
+    margin-bottom: 1rem;
+    clear: both;
 
     label, .input-group-addon {
         font-size: 1.2rem;
         border-right: none;
         color: @dark-gray;
         padding-bottom: 0.4rem;
-        padding-top: 0.4rem;
-        padding-left: 0.5rem;
-        padding-right: 0.5rem;
+        padding-right: 0.7rem;
+        padding-left: 0.7rem;
     }
 
     label:last-child, .input-group-addon:last-child {
 
     input[type="radio"]:checked + label{
         color: @black;
-        font-weight:bold;
+        font-weight: bold;
         border-bottom: @light-green 5px solid;
     }
     select {
 }
 
 #check-advanced:checked ~ #advanced-search-container {
-    display:block;
+    display: block;
 }
 
 .advanced {
-    margin-top:1rem;
-    text-align:right;
+    padding: 0;
+    margin-top: 0.3rem;
+    text-align: right;
 }

searx/static/themes/oscar/less/logicodev/search.less

 .search_categories, #categories {
   text-transform: capitalize;
   margin-bottom: 0.5rem;
+  display: flex;
+  flex-wrap: wrap;
+  flex-flow: row wrap;
+  align-content: stretch;
 
   label, .input-group-addon {
+    flex-grow: 1;
+    flex-basis: auto;
     font-size: 1.2rem;
-    font-weight:normal;
+    font-weight: normal;
     background-color: white;
     border: @mild-gray 1px solid;
     border-right: none;
     color: @dark-gray;
     padding-bottom: 0.4rem;
     padding-top: 0.4rem;
-    padding-left: 0.5rem;
-    padding-right: 0.5rem;
+    text-align: center;
   }
   label:last-child, .input-group-addon:last-child {
       border-right: @mild-gray 1px solid;
 
   input[type="checkbox"]:checked + label {
     color: @black;
-    font-weight:bold;
+    font-weight: bold;
     border-bottom: @light-green 5px solid;
   }
 }

searx/static/themes/oscar/less/pointhi/advanced.less

 #advanced-search-container {
-    display:none;
-    text-align:center;
-    margin-bottom:1rem;
+    display: none;
+    text-align: center;
+    margin-bottom: 1rem;
+    clear: both;
 
     label, .input-group-addon {
         font-size: 1.3rem;
         border-right: none;
         color: #333;
         padding-bottom: 0.8rem;
-        padding-top: 0.8rem;
         padding-left: 1.2rem;
         padding-right: 1.2rem;
     }
     label:last-child, .input-group-addon:last-child {
         border-right: #DDD 1px solid;
     }
-    
+
     input[type="radio"] {
         display: none;
     }
-    
-    input[type="radio"]:checked + label{
+
+    input[type="radio"]:checked + label {
         color: black;
-        font-weight:bold;
+        font-weight: bold;
         background-color: #EEE;
     }
 }
 }
 
 #check-advanced:checked ~ #advanced-search-container {
-    display:block;
+    display: block;
 }
 
 .advanced {
-    margin-top:1rem;
-    text-align:right;
+    padding: 0;
+    margin-top: 0.3rem;
+    text-align: right;
 }

searx/static/themes/oscar/less/pointhi/search.less

 .search_categories, #categories {
     text-transform: capitalize;
-    margin-bottom:1.5rem;
-    margin-top:1.5rem;
+    margin-bottom: 1.5rem;
+    margin-top: 1.5rem;
+    display: flex;
+    flex-wrap: wrap;
+    align-content: stretch;
 
     label, .input-group-addon {
+        flex-grow: 1;
+        flex-basis: auto;
         font-size: 1.3rem;
-        font-weight:normal;
+        font-weight: normal;
         background-color: white;
         border: #DDD 1px solid;
         border-right: none;
         color: #333;
         padding-bottom: 0.8rem;
         padding-top: 0.8rem;
-        padding-left: 1.2rem;
-        padding-right: 1.2rem;
+        text-align: center;
     }
 
     label:last-child, .input-group-addon:last-child {
 
     input[type="checkbox"]:checked + label{
         color: black;
-        font-weight:bold;
+        font-weight: bold;
         background-color: #EEE;
     }
 }

searx/templates/oscar/advanced.html

-<div class="input-group col-sm-12 advanced">
-    <input type="checkbox" name="advanced_search" id="check-advanced" {% if advanced_search %} checked="checked"{% endif %}>
-    <label for="check-advanced">
-        <span class="glyphicon glyphicon-cog"></span>
-        {{ _('Advanced settings') }}
-    </label>
-    <div id="advanced-search-container">
-        {% include 'oscar/categories.html' %}
-        {% include 'oscar/time-range.html' %}
-    </div>
+<input type="checkbox" name="advanced_search" id="check-advanced" {% if advanced_search %} checked="checked"{% endif %}>
+<label for="check-advanced">
+    <span class="glyphicon glyphicon-cog"></span>
+    {{ _('Advanced settings') }}
+</label>
+<div id="advanced-search-container">
+    {% include 'oscar/categories.html' %}
+    {% include 'oscar/time-range.html' %}
 </div>

searx/templates/oscar/categories.html

 {% if rtl %}
     {% for category in categories | reverse %}
         <input class="hidden" type="checkbox" id="checkbox_{{ category|replace(' ', '_') }}" name="category_{{ category }}" {% if category in selected_categories %}checked="checked"{% endif %} />
-        <label class="input-group-addon" for="checkbox_{{ category|replace(' ', '_') }}">{{ _(category) }}</label>
+        <label for="checkbox_{{ category|replace(' ', '_') }}">{{ _(category) }}</label>
         </label>
     {% endfor %}
 {% else %}
     {% for category in categories %}
         <input class="hidden" type="checkbox" id="checkbox_{{ category|replace(' ', '_') }}" name="category_{{ category }}" {% if category in selected_categories %}checked="checked"{% endif %} />
-        <label class="input-group-addon" for="checkbox_{{ category|replace(' ', '_') }}">{{ _(category) }}</label>
+        <label for="checkbox_{{ category|replace(' ', '_') }}">{{ _(category) }}</label>
     {% endfor %}
 {% endif %}
 </div>

searx/templates/oscar/search.html

             <button type="submit" class="btn btn-default"><span class="hide_if_nojs">{{ icon('search') }}</span><span class="hidden active_if_nojs">{{ _('Start search') }}</span></button>
         </span>
     </div>
-    {% include 'oscar/advanced.html' %}
+    <div class="input-group col-sm-12 advanced">
+        {% include 'oscar/advanced.html' %}
+    </div>
 </form><!-- / #search_form_full -->

searx/templates/oscar/search_full.html

             <button type="submit" class="btn btn-default input-lg"><span class="hide_if_nojs">{{ icon('search') }}</span><span class="hidden active_if_nojs">{{ _('Start search') }}</span></button>
         </span>
     </div>
-    <div class="input-group col-md-8 col-md-offset-2">
+    <div class="col-md-8 col-md-offset-2  advanced">
         {% include 'oscar/advanced.html' %}
     </div>