How do I edit the css style of elements within a list?

I want to add padding to the elements within a list using my css file, but it just pads the list object instead of the individual elements.

Just use in css style:

.myulclass li {
...
}

or ul.myulclass li {
...
}

<ul class="">
	<li>...</li>
	...
</ul>

Assuming the OP is referring to Construct's List object, that is based on a <select> HTML element, where items are <option> elements. It does not use <ul> or <li> elements, which are for things like bullet point lists in documents.

You can use CSS to style option elements too, but the range of styles browsers allow for styling them is limited. There's a new <selectmenu> element in development that allows for more advanced styling, but it's not been released in any browser yet.