style.css

.chatbox {
    display: flex!important;
    justify-content: center!important;
    align-items: center!important;
    position: fixed;
    visibility: visible;
    opacity: 1;
    right: 15px;
    bottom: 15px;
    z-index: 996;
    width: 100px;
    height: 100px;
    border-radius: 50px;
    border: 2px solid #cda45e;
}

.Chatbtn {
    width: 94px;
    height: 94px;
    background: radial-gradient(#cda45e 50%, rgba(205, 164, 94, .4) 52%);
    border-radius: 50%;
    display: block;
    position: relative;
    overflow: hidden;
    cursor: pointer;
    font-size: xx-large;
}

.chatwindow {
    position: fixed;
    bottom: 120px;
    right: 20px;
    max-height: 500px;
    width: 400px;
    background-color: rgb(245, 240, 240);
    flex-direction: column;
    justify-content: space-between;
    padding: .75rem;
    box-shadow: 5px 5px 5px rgb(0 0 0 / 40%);
    border-radius: 10px;
    overflow-y: scroll;
}

@media screen and (max-width: 500px) {
    .chatwindow {
        min-height: calc(100vh - 250px);
        width: 90vw !important;
        margin: 5px;
        right: 0px;
    }
}

.hide {
    display: none;
}