add max width to group header description

public/sass/components/_form_select_box.scss

@@ -172,18 +172,22 @@ $select-input-bg-disabled: $input-bg-disabled;
   margin-right: 10px;
 }
 
-.gf-form-select-box__option-group__header {
-  display: flex;
-  align-items: center;
-  justify-content: flex-start;
-  justify-items: center;
-  cursor: pointer;
-  padding: 7px 10px;
-  width: 100%;
-  border-bottom: 1px solid $hr-border-color;
-  text-transform: capitalize;
+.gf-form-select-box__option-group {
+  max-width: 600px;
+
+  .gf-form-select-box__option-group__header {
+    display: flex;
+    align-items: center;
+    justify-content: flex-start;
+    justify-items: center;
+    cursor: pointer;
+    padding: 7px 10px;
+    width: 100%;
+    border-bottom: 1px solid $hr-border-color;
+    text-transform: capitalize;
 
-  .fa {
-    padding-right: 2px;
+    .fa {
+      padding-right: 2px;
+    }
   }
 }