Fix middle vertical align on table cells

For merged cells, middle vertical alignment would not work properly (it
was either aligned to the top or bottom).

src/public/stylesheets/print.css

@@ -13,4 +13,11 @@
     .relation-map-wrapper {
         height: 100vh !important;
     }
+
+    .table thead th,
+    .table td, .table th {
+        /* Fix center vertical alignment of table cells */
+        vertical-align: middle;
+    }
+
 }

src/public/stylesheets/style.css

@@ -990,3 +990,9 @@ button.close:hover {
 textarea {
     cursor: auto;
 }
+
+.table thead th,
+.table td, .table th {
+    /* Fix center vertical alignment of table cells */
+    vertical-align: middle;
+}