style.css

body{
    background-color: rgb(56, 23, 9);
    padding-top: 100px;
}

.container{
    max-width: 500px;
    margin: auto;
    background-color: rgb(144, 0, 0);
    padding: 20px;
    border-radius: 10px;
}

h1{
    font-family: Arial, Helvetica, sans-serif;
    color: white;
    text-transform: uppercase;
    font-size: 24px;
    letter-spacing: 2px;
    text-align: center;
}

input{
    margin: auto;
    width: 70%;
    display: block; /*o elemento vai tampar toda linha, nao pode ter nada ao seu lado*/
    padding: 5px;
    box-sizing: border-box; /*para nao afetar o padding*/
    margin-bottom: 10px;
}

.buttonArea{
    display: flex;
    justify-content: center;
    margin-bottom: 20px;
}

button{
    margin-top: 10px;
    box-sizing: border-box;
    width: 100px;
    height: 25px;
    cursor: pointer;
}

.result{
    border-top: 1px solid white;
    max-width: 500px;
    line-height: 8px;
    color: white;
    font-family: Arial, Helvetica, sans-serif;
}