.findepantalla{
   width: 100%;
   position:fixed; bottom: 0px;top:auto;
z-index:5;
}

.whatsapp{
   width: 70px;
    position: fixed;
    bottom: 0px;
    top: auto;
    right: 0px;
    margin-bottom:0px !important;
    height: 70px;
    z-index: 5;
}

.back-to-top {
   position: fixed;
   bottom: 20px;
   left: 25px;
   width: 50px;
   height: 50px;
   border-radius: 50%;
   background: rgb(31 151 209);
   visibility: hidden;
   cursor: pointer;
   transition: all .2s ease;
   z-index: 1100;
   box-shadow: 1px 1px 6px 3px rgb(100 95 136 / 16%);
}

.back-to-top::after {
   content: "";
   position: absolute;
   top: 50%;
   left: 0;
   right: 0;
   margin: -4px auto;
   width: 12px;
   height: 12px;
   border-top: 2px solid rgb(255, 255, 255);
   border-right: 2px solid rgb(255, 255, 255);
   -webkit-transform: rotate(
-45deg);
   -moz-transform: rotate(-45deg);
   transform: rotate(
-45deg);
}