.scr_top{
opacity:0;
height:50px;
width:50px;

background-image:url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAYAAAAeP4ixAAAABGdBTUEAALGPC/xhBQAAAAlwSFlzAAAOwQAADsEBuJFr7QAAABh0RVh0U29mdHdhcmUAcGFpbnQubmV0IDQuMC41ZYUyZQAAAexJREFUaEPtlk1KQ0EQhEXwBOLaQ2TrJkYhaBbeKAcXjba+kqJT8z8THjIFH9Gern5dGUhy9fh8OP0HZpC1MYOsjRlkbcwga2NokG9dMaqnF8OG+xCm7fblfjn/4N4eDAniA0CoKU8r3YdiWcOLz5S3hV4D3+2VFw2Jexbv5/LaRLd3hhdMiXvVrBpaB2XfhBd73MwqmofwQqVir5pdQu2A6pvw4hm/s1+rPpprgnQLAfGs5RnFHwBVN8IP7iWeqZ6ZosTU/Sa8eLZ7dpIiAz9olPgZaocQOc1FN7Hbvd0ej8fr5d8/wbvZbG4e9vs7rnmhbrhdgqQas0PgnPtZqBk5M/l82SVKsokHKvG593ipvpjQz54QoYaqmwAhT6g3JnjIJ79ngkl5gBKf53i5ltPP4nPvBckgLK7h75jXgLiW62HhTHmNpiDKZ3AfhJqhPAb3hKR8RvdlDPSwUDOUB3AfCzXlMZJBFKqfQR8LNUN5GO7N9YYOzj61gOuToNerdkaOL3Z49gt0+5T3E5uXYOUsRPy8mY7gr+LcoUV0ClLExYKgZihPKzNIDCzsAwDlaWVokBDK08pFgvibUZ5WhgZhoWYoTyszSAxeWqE8rcwgMfziHuVpZchQA0tDI0MYwwZfmhlkbcwg6+Jw+gInXCrAyO91ZwAAAABJRU5ErkJggg==');
position:fixed;
bottom:30px;
margin:5px;
right:20px;
z-index:100;
-moz-transition: all 0.5s ease-in-out;
-webkit-transition: all 0.5s ease-in-out;
transition: all 0.5s ease-in-out;
border-radius:4px;
}