style.css

* {
    color: whitesmoke;
    outline: none;
}

body, html{
    margin: 0%;
    padding: 0%;
}

.App {
    text-align: center;
    width: 500px;
    background-color: #4f5663;
    margin: 0px auto;
    min-height: 200px;
    padding: 2rem 1.6rem;
    box-sizing: border-box;
}
  
.App h2 {
    margin: 1.5rem 0;
}

form {
    margin: 3rem 0px 1rem 0px;
}
  
form label, form input {
    display: block;
    text-align: center;
    font-size: 1.5rem;
    margin: 1rem auto;
    width: 90%;
}
  
form input {
    color: black;
    padding: 3px;
    border-radius: 10px;
}
  
.btn {
    margin: 1rem auto;
    text-align: center;
    outline: none;
    border-radius: 5px;
    font-size: 1.3rem;
    padding: 5px 15px;
    color: black;
}

.message {
    font-size: 1.2rem;
}

table, th, td {
    width: 100%;
    table-layout: fixed;padding: 0.2rem;
    color: black;
    background-color: #b9c2d3;
    border: 2px solid #2a2e35;
    border-collapse: collapse;
}

.output {
    background-color: whitesmoke;
}