[TheLastSuperman]

AdminCP > Styles & Templates > Style Manager > Edit Templates > *find CSS Templates and double-click to expand, now find:

.threadbit .threadlastpost dd {
	margin:0 20px 0 20px;
	height: {vb:math {vb:stylevar mid_fontSize}*{vb:stylevar line_height}};
	overflow: hidden;
	white-space:nowrap;
}

Change the margin value for right to 10px instead of 20px example:

.threadbit .threadlastpost dd {
	margin:0 10px 0 20px;
	height: {vb:math {vb:stylevar mid_fontSize}*{vb:stylevar line_height}};
	overflow: hidden;
	white-space:nowrap;
}

And in case some are wondering yes you can define them separately as in margin-left: 10px;margin-top:10px; however when you see it 0 10px 0 10px then it's different example:

0   10px   0    10px
T    R     B     L

Top, Right, Bottom, Left .