app.css

:root{
    background-color:#ecf5ff;
    font-size: 62.5%;
}

*{
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
    color:#333;
}

h1,
h2,
h3,
h4{
    margin-bottom: 1rem;
}

h1 {
    font-size: 5.4rem;
    color: #56a5eb;
    margin-bottom: 5rem;
  }
  
  h1 > span {
    font-size: 2.4rem;
    font-weight: 500;
  }
  
  h2 {
    font-size: 4.2rem;
    margin-bottom: 4rem;
    font-weight: 700;
  }
  
  h3 {
    font-size: 2.8rem;
    font-weight: 500;
  }

  /* UTILITIES */

  .container{
      width: 100vw;
      height: 100vh;
      display:flex;
      justify-content: center;
      align-items: center;
      max-width: 80rem;
      margin: 0 auto;
      padding: 2rem;
  }

.container>*{
    width: 100%;
}
.flex-column {
    display: flex;
    flex-direction: column;
  }
  
  .flex-center {
    justify-content: center;
    align-items: center;
  }
  
  .justify-center {
    justify-content: center;
  }
  
  .text-center {
    text-align: center;
  }
  
  .hidden {
    display: none;
  }
  
/* BUTTONS */
.btn {
    font-size: 1.8rem;
    padding: 1rem 0;
    width: 20rem;
    text-align: center;
    border: 0.1rem solid #56a5eb;
    margin-bottom: 1rem;
    text-decoration: none;
    color: #56a5eb;
    background-color: white;
  }
  
  .btn:hover {
    cursor: pointer;
    box-shadow: 0 0.4rem 1.4rem 0 rgba(86, 185, 235, 0.5);
    transform: translateY(-0.1rem);
    transition: transform 150ms;
  }
  
  .btn[disabled]:hover {
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
  }
  
  /* forms */
form{
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

input{
  margin-bottom: 1rem;
  width:20rem;
  padding:1.5rem;
  font-size:1.8rem;
  border:none;
  box-shadow: 0 0.1rem 1.4rem 0 rgba(86, 185, 235, 0.5);
}

input::placeholder{
  color:#aaa;
}