jQuery hover border color change

I have some navigation and now I want to change border-color of hover. For example I want to change:
#nav ul li a:hover border-color with jQuery. How to do that since this doesen't work:

Code:

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$("#nav ul li a:hover").css("border-bottom-color", "#ff1313");

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Are you using Firebug to debug this? Can you try putting this in the console window and telling me what it returns??

$("#nav ul li")