themes/sourcehut: add search input to mailbox view

themes/sourcehut/assets/style.css

@@ -5511,6 +5511,9 @@ body {
   .mailbox-container > .row, .message-container > .row {
     flex-grow: 1; }
 
+.mailbox-container form {
+  padding: 10px; }
+
 .mailboxes-column {
   border-right: 3px #ddd solid;
   padding: 0; }

themes/sourcehut/mailbox.html

@@ -40,6 +40,13 @@
       </ul>
     </div>
     <div class="col-md-10 messages-column">
+      <div class="nav flex-column">
+        <form method="get" action="">
+          <input type="text" name="query" value="{{.Query}}"
+            class="form-control" placeholder="Search">
+        </form>
+      </div>
+
       {{if .Messages}}
       <ul class="nav flex-column">
         {{range .Messages}}

themes/sourcehut/scss/main.scss

@@ -43,6 +43,10 @@ body {
   }
 }
 
+.mailbox-container form {
+  padding: 10px;
+}
+
 .mailboxes-column {
   border-right: 3px #ddd solid;
   padding: 0;