diff -u b/core/themes/seven/css/components/field-ui.css b/core/themes/seven/css/components/field-ui.css
--- b/core/themes/seven/css/components/field-ui.css
+++ b/core/themes/seven/css/components/field-ui.css
@@ -18,6 +18,9 @@
 #field-display-overview .field-plugin-settings-edit-form .form-submit {
   margin-bottom: 0;
 }
+#field-display-overview .form-item-fields-field-image-settings-edit-form-settings-image-style {
+  white-space: normal;
+}
 #field-display-overview .form-item-fields-field-image-settings-edit-form-settings-image-style .description {
   display: inline-block;
   margin-left: 1em; /* LTR */