main.css

* {
  margin: 0;
  padding: 0;
  -webkit-box-sizing: 0;
          box-sizing: 0;
}

html {
  font-size: 62.5%;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  text-transform: uppercase;
}

.container {
  height: 100vh;
  width: 100vw;
  background-color: aliceblue;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
}

h1 {
  color: var(--yellow);
  font-size: 20rem;
  font-weight: bold;
}

@media screen and (max-width: 900px) {
  h1 {
    font-size: 15rem;
  }
}

@media screen and (max-width: 450px) {
  h1 {
    font-size: 10rem;
  }
}

@media screen and (max-width: 250px) {
  h1 {
    font-size: 8rem;
  }
}

button {
  padding: 1rem 3rem;
  font-size: 2rem;
  outline: none;
  margin-top: 5rem;
  border-radius: 2rem;
  border: none;
  -webkit-transition: all .3s ease-in-out;
  transition: all .3s ease-in-out;
}

button:hover {
  cursor: pointer;
  padding: 1rem 4rem;
}

.animate {
  -webkit-animation: animate 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94) both;
  animation: animate 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94) both;
}

@-webkit-keyframes animate {
  0% {
    -webkit-transform: rotateY(20deg) rotateX(35deg) translate(300px, -300px) skew(-35deg, 10deg);
    transform: rotateY(20deg) rotateX(35deg) translate(300px, -300px) skew(-35deg, 10deg);
    opacity: 0;
  }
  100% {
    -webkit-transform: rotateY(0) rotateX(0deg) translate(0, 0) skew(0deg, 0deg);
    transform: rotateY(0) rotateX(0deg) translate(0, 0) skew(0deg, 0deg);
    opacity: 1;
  }
}

@keyframes animate {
  0% {
    -webkit-transform: rotateY(20deg) rotateX(35deg) translate(300px, -300px) skew(-35deg, 10deg);
    transform: rotateY(20deg) rotateX(35deg) translate(300px, -300px) skew(-35deg, 10deg);
    opacity: 0;
  }
  100% {
    -webkit-transform: rotateY(0) rotateX(0deg) translate(0, 0) skew(0deg, 0deg);
    transform: rotateY(0) rotateX(0deg) translate(0, 0) skew(0deg, 0deg);
    opacity: 1;
  }
}