.btn-left-line-mt {
    position: relative;
    isolation: isolate;
}

.btn-left-line-mt:before {
   content: '';
   position: absolute;
   width: 100%;
   height: 100%;
   top: 50%;
   left: 50%;
   border: 3px solid #9a674b;
   border-radius: 50%;
   transform: translate(-50%, -50%);
   animation: scale-grow 1.5s ease-in-out infinite;
   z-index: -1;
}


.btn-left-line-mt:hover::before {
    border: 3px solid #F3CC93;
}

@keyframes scale-grow {
  0% {
    transform: translate(-50%, -50%) scale(1);
    opacity: 0;
  }
  10% {
    transform: translate(-50%, -50%) scale(1);
    opacity: 1;
  }
  100% {
    transform: translate(-50%, -50%) scale(1.5);
    opacity: 0;
  }
}