Added css

css/islandora_fits.css

@@ -0,0 +1,9 @@
+.islandora_fits_table {
+    width: 50em;
+}
+.islandora_fits_table_labels {
+    width: 50%;
+}
+.islandora_fits_table_values {
+    width: 50%;
+}

islandora_fits.libraries.yml

@@ -0,0 +1,6 @@
+
+islandora_fits:
+  version: 1.x
+  css:
+    theme:
+      css/islandora_fits.css: {}

src/Plugin/Field/FieldFormatter/FitsFormatter.php

@@ -151,6 +151,11 @@ class FitsFormatter extends FormatterBase {
             '#title' => $this->t("FITS metadata"),
             '#link' => $link,
             '#output' => $output,
+            '#attached' => [
+                'library' => [
+                    'islandora_fits/islandora_fits',
+                ]
+            ]
 
         ];
         return \Drupal::service('renderer')->render($renderable);

templates/fits.html.twig

@@ -1,3 +1,6 @@
+{{ attach_library('css/islandora_fits') }}
+
+
 <h1>{{ title }}</h1>
 <p>{{ link }}</p>