#content {
  
  animation-name: snow_floor;
  animation-duration: 10s;
  animation-fill-mode: forwards;
}


#element {
  z-index: 5;
  position: absolute;
  width:  100%;
  height: 100%;

  top: -15%;
}

.sub_element {
  position: relative;
  
  border-radius: 50%;
  background-color: WhiteSmoke;
  
  animation-name: snow_ball;
  animation-iteration-count: infinite;
}

#sub_element_1 {
  
  margin-left: 15%;
  animation-duration: 3.75s;
  animation-delay: 0.5s;
}

#sub_element_2 {
  
  margin-left: 35%;
  animation-duration: 3.5s;
}

#sub_element_3 {

  margin-left: 55%;
  animation-duration: 3.25s;
}

#sub_element_4 {
  
  margin-left: 75%;
  animation-duration: 3s;
  animation-delay: 0.5s;
}


#sub_element_5 {
 
  margin-left: 25%;
  animation-duration: 7.25s;
}

#sub_element_6 {
  
  margin-left: 45%;
  animation-duration: 6.75s;
}

#sub_element_7 {
  
  margin-left: 65%;
  animation-duration: 6.5s;
  animation-delay: 1.5s;
}

#sub_element_8 {
  
  margin-left: 85%;
  animation-duration: 6.25s;
}

#sub_element_9 {
  
  margin-left: 7%;
  animation-duration: 6s;
}

#sub_element_10 {
  
  margin-left: 21%;
  animation-duration: 4.25s;
}

#sub_element_11 {

  margin-left: 35%;
  animation-duration: 4.5s;
  animation-delay: 1.5s;
}

#sub_element_12 {
  
  margin-left: 15%;
  animation-duration: 4.75s;
}

#sub_element_13 {
  
  margin-left: 55%;
  animation-duration: 5.75s;
}

#sub_element_14 {
  
  margin-left: 21%;
  animation-duration: 5.5s;
}

#sub_element_15 {
  
  margin-left: 45%;
  animation-duration: 5.25s;
}

#sub_element_16 {
  
  margin-left: 65%;
  animation-duration: 5s;
}

#sub_element_1, #sub_element_5, #sub_element_11, #sub_element_13{
  width:  20px;
  height: 20px;
}

#sub_element_2, #sub_element_6, #sub_element_10, #sub_element_14{
  width:  25px;
  height: 25px;
}

#sub_element_3, #sub_element_7, #sub_element_12, #sub_element_15{
  width:  15px;
  height: 15px;
  }

#sub_element_4, #sub_element_8, #sub_element_9, #sub_element_16{
  width:  13px;
  height: 13px;
}


@keyframes snow_ball{
      0%{top:     0%;}
      100%{top: 100%; width:  0px; height:  0px; }
}

@keyframes snow_floor{
      0%{ background-image: url("img/sand.png"); }
      100%{background-image: url("img/sand_with_snow.png");}
}