The ul and ol elements in HTML represent an unordered list and an ordered list, respectively. You can style the appearance of lists using CSS.

Here is an example of how to style the appearance of lists using CSS:

ul {
list-style-type: square;
padding: 0;
margin: 0;
}

ol {
list-style-type: decimal;
padding: 0;
margin: 0;
}

li {
margin: 10px 0;
line-height: 1.5;
}

In this example, the ul element is styled with a square list style and no padding or margin. The ol element is styled with a decimal list style and no padding or margin. The li element is styled with a margin of 10 pixels and a line height of 1.5.

You can also use the list-style-image property to use an image as the list style, or the list-style-position property to specify the position of the list style (inside or outside the list item).

ul {
list-style-image: url("my-list-style.png");
list-style-position: inside;
}

In this example, the ul element is styled with an image as the list style, and the list style.