NextGen gallery: align multiple galleries

Hello,

I’m trying to align multiple slideshows horizontally with NextGen.

The effect that I’m after is this (please note that’s not the site I’m building).

I thought that floating the slideshows left would work, but it didn’t – this is how I customised the CSS:

/* ----------- Slideshow -------------*/
.slideshow {
	overflow: hidden;
	margin: auto;
	float: left;
	display:inline-block;
	text-align:center;
	outline: none;
}

.slideshowlink {

}

/* ----------- JS Slideshow -------------*/
.ngg-slideshow {
	float: left;
	padding-right:10px;
	margin-bottom:40px;
	overflow: hidden;
	position: relative;
}

Any help or tips would be greatly appreciated!