Add cancel button to search bar

assets/css/default.css

@@ -162,6 +162,15 @@ img.thumbnail {
   -webkit-appearance: none;
 }
 
+/* https://stackoverflow.com/a/55170420 */
+input[type="search"]::-webkit-search-cancel-button {
+  -webkit-appearance: none;
+  height: 14px;
+  width: 14px;
+  background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAB4AAAAeCAYAAAA7MK6iAAAAn0lEQVR42u3UMQrDMBBEUZ9WfQqDmm22EaTyjRMHAlM5K+Y7lb0wnUZPIKHlnutOa+25Z4D++MRBX98MD1V/trSppLKHqj9TTBWKcoUqffbUcbBBEhTjBOV4ja4l4OIAZThEOV6jHO8ARXD+gPPvKMABinGOrnu6gTNUawrcQKNCAQ7QeTxORzle3+sDfjJpPCqhJh7GixZq4rHcc9l5A9qZ+WeBhgEuAAAAAElFTkSuQmCC);
+  background-size: 14px;
+}
+
 .navbar > .searchbar .pure-form fieldset {
   padding: 0;
 }