:root {
    --header-height: 72px;
    --footer-height: 32px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
}

.section {
    padding-bottom: 20px;
}

.main-top {
    height: calc(100vh - var(--header-height) - var(--footer-height));
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px 0;
}

.main-content {
    min-height: calc(100vh - var(--footer-height));
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px 0;
}

.footer {
    height: var(--footer-height);
    background: #f8f9fa;
    display: flex;
    justify-content: center;
    align-items: center;
}

#myBtn {
    display: none;
    position: fixed;
    bottom: 20px;
    right: 30px;
    z-index: 99;
    font-size: 18px;
    border: none;
    outline: none;
    background-color: #ccc;
    color: white;
    cursor: pointer;
    padding: 15px;
    border-radius: 4px;
    z-index: 10;
}

#myBtn:hover {
    background-color: #555;
}