.flex-1 {
    flex: 1;
}

.message-list {
    min-width: 140px;
}

.chat-list {
    min-width: 105px;
    width: 105px;
    border-right: 1px solid lightgray;
}

@media (min-width: 576px) {
    .chat-list {
        width: 200px;
    }
}

@media (min-width: 768px) {
    .chat-list {
        width: 320px;
    }
}

@media (min-width: 992px) {
    .chat-list {
        width: 400px;
    }
}