Кнопка и слайд вниз

.hidden { 
  width: 3px; 
  height: 300px; 
  margin: auto; 
  background: repeating-linear-gradient(#000 0, #000 20px, #fff 0%, #fff 25px); 
  animation: move 3s linear infinite; 
} 
 
@keyframes move { 
  0% { 
    height: 50px; 
    opacity: .9; 
  } 
}

<div class="hidden"></div>

.btn { 
  width: 150px; 
  height: 50px; 
  border: 2px solid darkred; 
  margin: 50px 100px; 
  border-radius: 50px/100px; 
  background: tomato; 
  position: relative; 
} 
 
.btn:after { 
  content: ""; 
  display: block; 
  width: 250px; 
  height: 5px; 
  background: linear-gradient(to right, #000 0%, #000, #000); 
  position: absolute; 
  left: -50%; 
  top: 40%; 
  z-index: 0; 
  z-index: -1; 
} 
 
.btn:before { 
  content: ""; 
  display: block; 
  width: 250px; 
  height: 5px; 
  background: linear-gradient(to right, #000 0%, #000, #000); 
  position: absolute; 
  left: -30%; 
  top: 60%; 
  z-index: 0; 
  z-index: -1; 
}

<div class="btn"></div>