Indicate failed searches by background color.

static/c4.css

@@ -46,21 +46,6 @@ h1, h1 a  {
     font-size: smaller;
 }
 
-#knowntypes button {
-    color: #220;
-    background-color: #dfaa37;
-    border: 1px solid #220;
-    border-radius: 4px;
-    padding: 0.2em 0.4em;
-    margin: 0.2em;
-    font-weight: bolder;
-    cursor: pointer;
-}
-
-#knowntypes button:hover, #knowntypes button:focus {
-    background-color: #f5c251;
-}
-
 .btn {
   box-shadow: 0 3px 6px -1px rgba(0,0,0,0.3);
 }

static/form.js

@@ -65,22 +65,8 @@ function knownTypes() {
       map[i.type] = true;
     }
   }
-
-  // Get location in document.
-  const known_types = document.getElementById('knowntypes');
-  known_types.textContent = `Known types: `;
-
-  // Create a button for every known type.
-  for (let label of Object.keys(map).sort()) {
-    btn = document.createElement('button');
-    btn.setAttribute('type', 'button');
-    btn.textContent = label;
-    btn.addEventListener('click', function() {
-      document.getElementById('type').value = label;
-    });
-
-    known_types.appendChild(btn);
-  }
+  let types = Object.keys(map).sort().join(', ')
+  document.getElementById('knowntypes').textContent = `Known types: ${types}.`;
 }
 
 function save() {