.square { float:left; position: relative; width: 100px; padding-bottom : 100px; /* = width for a 1:1 aspect ratio */ margin:1.66%; background-position:center center; background-repeat:no-repeat; background-size:cover; /* you change this to "contain" if you don't want the images to be cropped */ } .img_1{background-image:url('2015/last4/1.jpg');} .img_2{background-image:url('2015/last4/2.jpg');} .img_3{background-image:url('2015/last4/3.jpg');} .img_4{background-image:url('2015/last4/4.jpg');} .img_5{background-image:url('2015/last4/5.jpg');} .img_6{background-image:url('2015/last4/6.jpg');} .img_7{background-image:url('2015/last4/7.jpg');} .img_8{background-image:url('2015/last4/8.jpg');} .img_9{background-image:url('2015/last4/9.jpg');} .img_10{background-image:url('2015/last4/10.jpg');} .img_11{background-image:url('2015/last4/11.jpg');} .img_12{background-image:url('2015/last4/12.jpg');} .img_13{background-image:url('2015/last4/13.jpg');} .img_14{background-image:url('2015/last4/14.jpg');} .img_15{background-image:url('2015/last4/15.jpg');} .img_16{background-image:url('2015/last4/16.jpg');} .img_17{background-image:url('2015/last4/17.jpg');} .img_18{background-image:url('2015/last4/18.jpg');} .img_19{background-image:url('2015/last4/19.jpg');} .img_20{background-image:url('2015/last4/20.jpg');}