JSFiddle - React, Tailwind, and code Playground

HTML

<header class="header">
   <div class="header__logo-box">
     <img src="https://dtgxwmigmg3gc.cloudfront.net/imagery/assets/derivations/icon/256/256/true/eyJpZCI6ImE4OWEzMGU2YTg5NTViYjcxZWY1OTJiNDlkYjZjMTRhLmpwZyIsInN0b3JhZ2UiOiJwdWJsaWNfc3RvcmUifQ?signature=8735e0713b1bd34828e75056d2c51efc7ffc62c0167dcb80e7d66fe8550b9bc6" alt="Logo" class="header__logo">
   </div>

   <div class="header__text-box">
     <h1 class="heading-primary">
       <span class="heading-primary--main">Outdoors</span>
       <span class="heading-primary--sub">is where life happens</span>
     </h1>

     <a href="#section-tours" class="btn btn--white btn--animated">Discover our tours</a>
   </div>
</header>

CSS

.header
{
  background-image: url(https://images2.minutemediacdn.com/image/upload/c_crop,h_2450,w_4368,x_0,y_165/f_auto,q_auto,w_1100/v1562080363/shape/mentalfloss/29942-gettyimages-155302141.jpg);
  background-blend-mode: multiply;
  height: 80vh;
  clip-path: polygon(0 0, 100% 0, 100% 100%, 0% 70%);
  position: relative;
}

.header::after
{
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: linear-gradient(to bottom right, #34c9eb, #0c4f5e);
  opacity: 0.9;
  z-index: -1;
}

.header__logo-box
{
  position: absolute;
  top: 5px;
  left: 0;  
  width: 80px;
}

.header__logo
{
  width: 100%;
  height: 100%;
}

.header__text-box
{
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.heading-primary--main
{
  display: block;
}

.heading-primary--sub
{
  display: block;  
}

.btn
{
  padding: 10px 30px;  
  text-decoration: none;
  color: inherit;
  border-radius: 100px;
  position: relative;
}

.btn--white
{
  background-color: #fff;
}

.btn::after
{
  position: absolute;
  content: "";
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;  
  transition: all .4s;
  background-color: red;
  z-index: -1;
  border-radius: 100px;
}

.btn:hover::after
{
  transform: scaleX(1.4) scaleY(1.6);
  opacity: 0;
}

/* this animation not working */
@keyframes fromBottom
{
  0%
  {
    opacity: 0;
    transform: translateY(100px);
  }
  
  100%
  {
    opacity: 1;
    transform: translateY(0);
  }
}

.btn--animated
{
  animation: fromBottom .5s ease-out;  
}