index.css

*{
    margin: 0;
    box-sizing: border-box;
}
body{
  font-family: sans-serif;
  margin: 0px;
  padding: 0px;
  text-align: center;
  height: 700px;
  background: linear-gradient(to bottom, black 20%, darkviolet 100%);
}
h1, p{
  color: white;
}
p{
  font-size: 15px;
  margin-bottom: 40px;
  opacity: 0.7;
}
h1{
  margin-top: 40px;
  margin-bottom: 10px;
  opacity: 0.9;

}
button{
  font-family: sans-serif;
  background-color: blueviolet;
  width:100%;
  line-height: 30px;
  font-weight: bold;
  text-transform: uppercase;
  cursor:pointer;
  border-radius: 30px;
  padding: 10px;
  transition: filter .5s;
}
/*pseudo-class*/
button:hover{
  color: antiquewhite;
  filter: brightness(1.2);
}
input{
  border-radius: 30px;
  margin-bottom: 15px;
  font-family: sans-serif;
  text-align: center;
  width:100%;
  padding: 15px;
  border: 2px solid black;
}
#corpo{
  margin-top: 40px;
  width: 60%;
  margin-inline : auto;
  max-width: 400px;
}
#resposta{
  margin-top: 30px;
  transition: opacity 1s;
  color: white;
}
#resposta div{
  font-size: 16px;
  opacity: 0.9;
  margin-bottom: 10px;
  color: white;
  }