Chrome is giving me troubles with css, need some help

I’m setting a new theme for my blog and the slider I got on the main page is sometimes covers my right sidebar – only in chrome!

small part of my css:

#featured {
	padding: 3px;
	height: auto;
	width: auto;
	background-color: #EEEEEE;
	border: 1px solid #D5D5D5;
	margin-top: 0px;
	margin-right: 3px;
	margin-bottom: 3px;
	margin-left: 0px;
}

How can i fix its width in a way it won’t move? If i change the width to 30% for example it will change positions and relocate on the right sidebar (that will happen randomly 7 times out of 10 refreshes.)

Edit: I’m working on this theme locally so i don’t got an url to post here but i would be more them happy to post any file that could help you help me.

Thanks