index.css

/* Comentário 
para várias linhas */

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

body{
  background-color: black;
  color: white;
  text-align: center;
  font-family: sans-serif;
}

#container{
  margin-top: 100px;
  width: 80%;
  max-width: 400px;
  margin-inline: auto;
}

h1{
  margin-top: 40px;
  margin-bottom: 10px;
  opacity: 0.9;
}

p{
  margin-bottom: 40px;
  opacity: 0.7;
}

input, button{
  display: block;
  width: 100%;
  padding: 20px;
  font-size: 20px;
  border-radius: 4px;
}

input{
  margin-bottom: 20px;
}

button{
  border: none;
  background-color: blueviolet;
  color: white;
  transition: filter .2s;
}

button:hover{
  filter: brightness(1.2);
  cursor: pointer;
}

#resposta{
  margin-top: 30px;
  transition: opacity 1s;
}

#resposta div{
  font-size: 16px;
  font-weight: normal;
  opacity: 0.9;
  margin-bottom: 10px;
}