Add some aria attributes

src/client/components/AntibodiesTable.vue

 <template>
-  <section class="data-table">
+  <section class="data-table" :aria-busy="isFetchingAntibodies">
     <div class="table-header">
       <AntibodiesTableTotal />
       <AntibodiesTableDownload />
@@ -79,7 +79,7 @@
             data-label="ID"
             class="link-cell"
           >
-            <span class="loader" v-if="isFetchingAntibodies"></span>
+            <span class="loader" v-if="isFetchingAntibodies" role="progressbar"></span>
             <RouterLink v-else :to="{ name: 'AntibodyPage', params: { hashId: antibody.hashId } }">
               {{ antibody.id }}
             </RouterLink>
@@ -88,28 +88,28 @@
             headers="antibodies-species"
             data-label="SPECIES"
           >
-            <span class="loader" v-if="isFetchingAntibodies"></span>
+            <span class="loader" v-if="isFetchingAntibodies" role="progressbar"></span>
             <i v-else>{{ antibody.species }}</i>
           </td>
           <td
             headers="antibodies-heavy-chain"
             data-label="HEAVY CHAIN"
           >
-            <span class="loader" v-if="isFetchingAntibodies"></span>
+            <span class="loader" v-if="isFetchingAntibodies" role="progressbar"></span>
             <span v-else>{{ antibody.heavyChain.sequence.substring(0, 15) }}...</span>
           </td>
           <td
             headers="antibodies-light-chain"
             data-label="LIGHT CHAIN"
           >
-            <span class="loader" v-if="isFetchingAntibodies"></span>
+            <span class="loader" v-if="isFetchingAntibodies" role="progressbar"></span>
             <span v-else>{{ antibody.lightChain.sequence.substring(0, 15) }}...</span>
           </td>
           <td
             headers="antibodies-sources"
             data-label="SOURCES"
           >
-            <span class="loader" v-if="isFetchingAntibodies"></span>
+            <span class="loader" v-if="isFetchingAntibodies" role="progressbar"></span>
             <span v-else>{{ listSources(antibody).join(', ') }}</span>
           </td>
         </tr>
@@ -207,6 +207,10 @@ function listSources(antibody: Antibody): string[] {
   white-space: nowrap;
 }
 
+span[role=progressbar] {
+  vertical-align: middle;
+}
+
 @media screen and (width < 700px) {
   .table-header {
     justify-content: center;

src/client/components/TheDownloadPage.vue

@@ -19,7 +19,8 @@
     <div
       v-else
       class="spinner"
-    ></div>
+      role="progressbar">
+    </div>
   </div>
 </template>