@media (max-width:500px) {
    .block-menu {
        display: flex;
        align-items: center;
        justify-content: center;
        flex-direction: column;
        padding-top: 20px;
        padding-bottom: 20px;
    }

    .logo-csd {
        margin-left: 0px;
    }

    .line-menu {
        display: flex;
        margin-top: 0px;
        flex-wrap: wrap;
        margin-left: 0px;
        margin-right: 0px;
        align-items: center;
        justify-content: center;
        padding-left: 0px;
    }

    .main-menu {
        color: #164463;
        margin: 10px;
    }

    .about-us {
        display: flex;
        flex-direction: column;
        width: 100%;
        min-width: 250px;
        max-width: 800px;
        align-items: center;
        justify-content: center;
    }

    .big-promo {
        display: none;
        width: 100%;
        justify-content: center;
        background-color: #494949;
        padding-top: 5px;
        padding-bottom: 5px;
    }

    .s-promo {
        display: flex;
        width: 100%;
        justify-content: center;
        background-color: #494949;
        padding-top: 5px;
        padding-bottom: 5px;
    }
}