Hi in bootstrap carousel every time it scrolls the item it add class .left
or right
according to your navigation to .item
in your case you wrote style for .left class like
#project .left {
background: url("../images/arrow_left_home.png") no-repeat scroll center center rgba(0, 0, 0, 0);
height: 38px;
top: 43%;
}
there you having top value please change the class name or top value..it will work.hope it will help