Add flex fallback for IE 9 and lower.

themes/bootstrap3/css/flex-fallback.css

+/* Broken up due to IE selector length limits */
+@media (min-width: 768px) {
+  /* Search */
+  .author-facets .author-list,
+  .result .media,
+  .result .record-checkbox,
+  .result .record-number,
+  .grid-result .grid-body,
+  .grid-result .grid-checkbox {
+    display: table-cell;
+    min-width: 20px;
+    vertical-align: top;
+  }
+  /* Layout */
+  .combined-search-container .combined-column,
+  .date-fields .date-from,
+  .date-fields .date-top,
+  .footer-container .footer-column,
+  .home-facet-container .home-facet,
+  .home-facet-container .home-facet-list,
+  .solr-facet-container .solr-adv-facet {
+    display: table-cell;
+    min-width: 20px;
+    vertical-align: top;
+  }
+}

themes/bootstrap3/theme.config.php

@@ -8,6 +8,7 @@ return array(
         //'bootstrap-custom.css',
         'compiled.css',
         'print.css:print',
+        'flex-fallback.css:lt IE 10', // flex polyfill
     ),
     'js' => array(
         'vendor/base64.js:lt IE 10', // btoa polyfill