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;
  }