.canvas_box {
  width: 100%;
  height: 900px;
  position: relative;
}

.canvas_box img {
  position: absolute;
  left: 50px;
  bottom: 100px;
}

.big_box {
  background:url('../imgs/bg.jpg') no-repeat top left;
  background-size: 100% 857px;
}
header{
  margin: 0;
  padding-top: 40px;
}
footer{
  margin-top: 0;
}