#btn-top {

    position: fixed;

    left: 50%;

    bottom: 25px;

    transform: translateX(-50%) translateY(20px);

    width: 58px;
    height: 58px;

    border: none;

    border-radius: 50%;

    background: linear-gradient(135deg, #0d63c9, #004694);

    color: #ffffff;

    font-size: 24px;

    font-weight: bold;

    cursor: pointer;

    z-index: 999999999;

    display: flex;

    align-items: center;

    justify-content: center;

    opacity: 0;

    visibility: hidden;

    box-shadow:
        0 12px 30px rgba(0,70,148,0.45);

    transition:
        opacity 0.3s ease,
        transform 0.3s ease,
        background 0.3s ease;

}

#btn-top:hover {

    background: linear-gradient(135deg, #1976e3, #0052b8);

    transform: translateX(-50%) translateY(-4px);

}

@media screen and (max-width: 768px) {

    #btn-top {

        width: 52px;
        height: 52px;

        font-size: 22px;

        bottom: 20px;

    }

}