Just set your width to auto:
#myWorkContent{
width: auto;
height:210px;
border: 13px solid #bed5cd;
overflow-x: scroll;
overflow-y: hidden;
white-space: nowrap;
}
This way your div can be as wide as possible, so you can add as many kitty images as possible ;3
Your div's width will expand based on the child elements it contains.