Change individual menu widget twenty ten

You need to install and use a browser inspector, if you are using firefox it would be firebug, other browsers have an equivalent addon.
Using the browser inspector, you will be able to see the css used on the menu and widget you are interested in.

Then when you are customising your css please use either a custom css method (some themes have this, there is also a plugin), OR use a child theme:
creating a child theme https://codex.www.ads-software.com/Child_Themes

Thanks Ross,

Yes I already use the inspector of the browser.
To be specific, I need to remove a top-border from my second menu widget.

This code gives border-top to all menu items:

.widget-area ul ul li {
padding: 3px;
border-top: solid 1px #000;
width: 103px;
}

I have tried all kinds of CSS to remove it but still can’t figure it out.
Any help is appreciated.

my website:
https://practice.timbeek.com/

Do you mean the wide space between “Various” and “Music Packs” ?

It is caused by the bottom margin of the .widget-container

Try this
#nav_menu-3 {
border-top: none;
}

Perfect Mohamed Asfer! that worked, thank you.
Also thanks Ross for the effort.