How to increase the height of a dropdown content for jquery selectize

I have a question that has a dropdown values of more than 10k values. We used jquery with selectize to do the value selection. However, the dropdown-content has a height which can display one value. How can we be able to increase the height so that more values are shown?
We have these 2 lines shown below in the Look and Feel -> General -> Header
https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/css/selectize.min.css" rel="stylesheet" />
">https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/js/standalone/selectize.min.js">
The javascript use is:
Qualtrics.SurveyEngine.addOnReady(function()
{
var controlId = this.questionId;
/*Place your JavaScript here to run when the page is fully displayed*/
jQuery.ajax({
method: "GET",
url: "https://cheeann89.github.io/jsonapi/publications.json",
dataType: "json",
success: function (result) {
jQuery("#"+ controlId).find('input:first').selectize({
maxItems: 1,
valueField: 'JournalTitle',
labelField: 'JournalTitle',
searchField: 'JournalTitle',
options: result
});
}
});
});
This is shown on the survey form:
Thanks.
Angela