* {
  box-sizing: border-box;
}

body {
  background-color:#e9ebf5;
  margin: 0;
  font-family: Montserrat, sans-serif;
  color: #1B2522;

  --title-duration: 500ms;
  --sub-title-duration: 500ms;
  --nav-duration: 200ms;
  --btn-grow-duration: 200ms;
  --scroll-down-duration: 200ms;

  --sub-title-delay: calc(var(--title-duration) - 200ms);
  --nav-delay: calc(var(--sub-title-delay) + var(--sub-title-duration));
  --btn-grow-delay: var(--nav-delay);
  --scroll-down-delay: var(--nav-delay);
}

.full-screen-header {
  height: 100vh;
  background-image: url('img/header_image.jpg');
  background-size: cover;
  background-position-x: 40%;
  background-position-y: center;

  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;

  color: white;
  position: relative;
  overflow: hidden;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #1B2522;
  padding: .75rem 1rem;
}

.nav-top {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1;

  animation: nav-enter var(--nav-duration) var(--nav-delay) backwards;
}

.logo {
  width: 30px;
}

.nav-list {
  margin: 0;
  padding: 0;
  display: flex;
  list-style-type: none;
}

.nav-list a {
  text-decoration: none;
  margin-left: 1rem;
  color: white;

  transition: color 100ms;
}

.nav-list a:hover {
  color: #CCC;
}

.title {
  font-size: 3rem;
  margin: 0;

  animation: title-enter var(--title-duration);
}

.sub-title {
  font-size: 1.5rem;
  margin-top: .3rem;
  margin-bottom: 1rem;

  animation: sub-title-enter var(--sub-title-duration) var(--sub-title-delay) backwards;
}

.scroll-down-icon {
  position: absolute;
  bottom: 1rem;
  width: 30px;

  animation:
    scroll-down-bounce calc(var(--scroll-down-duration) + var(--scroll-down-delay)) 1s alternate infinite linear,
    scroll-down-enter var(--scroll-down-duration) var(--scroll-down-delay) backwards;
}

.section {
  padding: 2rem;
}

.section-title {
  margin: 0;
  margin-bottom: 2rem;
  font-size: 2rem;
  text-align: center;
  color: black;
}

@keyframes scroll-down-bounce {
  from {
    transform: translateY(0);
  }

  to {
    transform: translateY(-10px);
  }
}

@keyframes shake {
  25% {
    transform: rotate(5deg);
  }

  75% {
    transform: rotate(-5deg);
  }
}

@keyframes title-enter {
  from {
    transform: translateX(-100vw);
  }
}

@keyframes sub-title-enter {
  from {
    transform: translateX(100vw);
  }
}

@keyframes nav-enter {
  from {
    transform: translateY(-100%);
  }
}

@keyframes btn-grow-enter {
  from {
    transform: scale(0);
  }
}

@keyframes scroll-down-enter {
  from {
    transform: scale(0) rotate(180deg);
  }
}

@media (max-width: 700px) {
  .full-screen-header {
    background-position-x: 65%;
  }
}


.btn:hover,
.btn:focus {
  background-color: hsl(261, 20%, 37%);
}

.wrapper {
  margin-top: 1rem;
  text-align: center;
}