Add search bar to channel page.

Closes #1923

assets/css/default.css

@@ -163,6 +163,13 @@ img.thumbnail {
   top: -0.7em;
 }
 
+.search-button {
+    border: none;
+    color: #3E4446;
+    background: transparent;
+    font-size: 1.1em;
+}
+
 /*
  * Navbar
  */
@@ -421,6 +428,13 @@ body.dark-theme {
   color: inherit;
 }
 
+.dark-theme .search-button {
+    border: none;
+    color: #B0ADA4;
+    background: transparent;
+    font-size: 1.1em;
+}
+
 .dark-theme .pure-menu-link:hover, .dark-theme .pure-menu-link:active {
   background-color: rgb(34, 36, 38)
 }
@@ -504,3 +518,7 @@ hr {
   order: 1;
   margin-top: 20px;
 }
+
+#content-navigation {
+    margin-bottom: 0.5em;
+}

src/invidious/views/channel.ecr

@@ -38,7 +38,7 @@
     <%= rendered "components/subscribe_widget" %>
 </div>
 
-<div class="pure-g h-box">
+<div class="pure-g h-box" id="content-navigation">
     <div class="pure-u-1-3">
         <!-- <a href="https://www.youtube.com/channel/<%= channel.ucid %>"><%= translate(locale, "View channel on YouTube") %></a> -->
         <!--             <a href="/redirect?referer=<%= env.get?("current_page") %>"><%= translate(locale, "Switch Invidious Instance") %></a> -->
@@ -67,6 +67,17 @@
                       </a>
                   <% end %>
               </li>
+              <li class="pure-menu-item navbar" style="margin: 0 0 0 0.5em">
+                  <div class="searchbar">
+                      <form class="pure-form" action="/search" method="get">
+                          <fieldset>
+                              <button class="search-button"><i class="icon ion-md-search"></i></button>
+                              <input type="search" name="q" placeholder="<%= translate(locale, "search") %>" value="<%= env.get?("search").try {|x| HTML.escape(x.as(String)) } %>">
+                              <input type="hidden" name="channel" value="<%= channel.ucid %>">
+                          </fieldset>
+                      </form>
+                  </div>
+              </li>
           </ui>
         </div>
     </div>