html,
body {
    width: 100%;
    height: 100%;
    position: fixed;
    left: 0;
    top: 0;
    overflow: hidden;
}

.pages {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.btn:active {
    transform: scale(0.98);
}

* {
    padding: 0;
    margin: 0;
}