html, body { 
    margin: 0; 
    height: 100vh; 
    width: 100%;
    text-align: center;
}

.header {
    padding: 12px 0 12px 0;
}

.btn {
    height: 32px;
}

.btn:first-child {
    margin-right: 10%;
}

.result {
    height: 100%;
    width: 100%;
}