How to change the arrow color of ' select' in a form with CSS [duplicate]

This question already has an answer here:

• How to style a <select> dropdown with CSS only without JavaScript? 19 answers

I currently have a form with a transparent background on a black page background and am unable to see the arrow on the 'select' in a drop down menu. Can someone please shed some light on how to change the color of the arrow?

<p class="wysija-paragraph wysija-date">
<label>Birthday</label>
<select class="wysija_date_day " name="wysija[field][cf_1][day]" placeholder="Day">
  <option>example option</option>
  <option>example option</option>
  <option>example option</option>
<select class="wysija_date_month " name="wysija[field][cf_1][month]" placeholder="Month">
  <option>example option</option>
  <option>example option</option>
  <option>example option</option>
<select class="wysija_date_year " name="wysija[field][cf_1][year]" placeholder="Year">
  <option>example option</option>
  <option>example option</option>
  <option>example option</option>
</p>