html {
    font-family: Arial;
    font-size: 16px;
}

.container {
    width: 1000px;
}

@media (max-width: 1000px) {
    .container {
        padding: 0 10%;
    }
}

#nahoru {
    position: fixed;
    right: 20px;
    bottom: 20px;
    width: 50px;
    height: 50px;
    font-size: 40px;
    background: rgb(135, 206, 250);
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 15px;
    cursor: pointer;
    opacity:0;
    transition: opacity 0.5s linear;
}

#nahoru.zobrazit {
    opacity: 1;
}