使用jquery更改边框底端颜色?

$("selector").css("border-bottom-color", "#fff");

1. #mydiv $("#mydiv")
2. .css()

$('#elementid').css('border-bottom', 'solid 1px red');

hilight_css = {"border-bottom-color":"red", 
               "background-color":"#000"};
$(".msg").css(hilight_css);

approach

.hilight { border-bottom-color:red; background-color:#000; }
.msg { /* something to make it notifiable */ }

$(".msg").addClass("hilight");
// to bring message block to normal
$(".hilight").removeClass("hilight");

.myApp
{
    border-bottom-color:#FF0000;
}

<div id="myDiv">test text</div>

$("#myDiv").addClass('myApp');// to add the style

$("#myDiv").removeClass('myApp');// to remove the style

$("#myDiv").css( 'border-bottom-color','#FF0000');