* {
  margin: 0px;
  padding: 0px;
  box-sizing: border-box;
}

body {
  font-family: 'Poppins', sans-serif;
}

header {
  display: flex;
  width: 90%;
  height: 10vh;
  margin: auto;
  align-items: center;
}

.logo-container,
.nav-links {
  display: flex;
}

.logo-container {
  flex: 1;
}
.logo {
  font-weight: 400;
  margin: 5px;
}

nav {
  flex: 2;
}

.nav-links {
  justify-content: space-around;
  list-style: none;
}

.nav-link {
  color: #5f5f79;
  font-size: 18px;
  text-decoration: none;
}

.presention {
  display: flex;
  width: 90%;
  margin: auto;
  min-height: 80vh;
  align-items: center;
}
.introduction {
  flex: 1;
}
.intro-text h1 {
  font-size: 44px;
  font-weight: 500;
  margin-bottom: 20%;
  word-wrap: break-word;
  background: linear-gradient(to right, #494964, #6f6f89);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.intro-text p {
  margin-top: 5px;
  font-size: 15px;
  color: #585772;
}

.cover {
  flex: 1;
  padding-left: 15em;
}
.cover img {
  height: 20vh;
  filter: drop-shadow(0px 5px 3px black);
  animation: drop 1.5s ease;
}
.big-circle {
  position: absolute;
  top: 0px;
  right: 0px;
  z-index: -1;
  height: 80%;
  opacity: 0.5;
}
.mid-circle {
  position: absolute;
  top: 30%;
  right: 30%;
  z-index: -1;
  height: 60%;
  opacity: 0.4;
}
.small-circle {
  position: absolute;
  bottom: 0%;
  left: 20%;
  z-index: -1;
}

@keyframes drop {
  0% {
    opacity: 0;
    transform: translateY(-80px);
  }
  100% {
    opacity: 1;
    transform: translateY(0px);
  }
}

@media screen and (max-height: 736px) {
  body {
    flex-direction: column;
  }

  .presention {
    flex-direction: column;
  }
  .nav-links {
    font-size: 5px;
  }
  .introduction {
    margin-top: 5vh;
    text-align: center;
  }
  .intro-text h1 {
    font-size: 30px;
    padding-right: 1em;
  }
  .intro-text p {
    font-size: 18px;
    padding-right: 2em;
  }
  .cover {
    padding-right: 17em;
    height: 5vh;
  }
  .cover img {
    height: 15vh;
  }
}