I tried to add images into DropDownList for each items in it, using only HTML and CSS. Here is my code, but it doesn't work.
<!DOCTYPE html>
<html>
<head>
<style>
select option[value="en"]::before { content: url("https://www.countryflags.io/gb/flat/24.png"); }
select option[value="vn"]::before { content: url("https://www.countryflags.io/vn/flat/24.png"); }
select option[value="th"]::before { content: url("https://www.countryflags.io/th/flat/24.png"); }
</style>
</head>
<body>
<select>
<option value="en">English</option>
<option value="vn">Vietnamese</option>
<option value="th">Thai</option>
</select>
</body>
</html>
Does anybody know how to solve this issue?