@media only screen and (max-width: 600px) {
    #list-challenge-title {
        font-size: 2.5rem;
        text-align: center;
    }
}

.card-title {
    font-weight: bold !important;
}

.challenge {
    margin: 10px 0 0 0;
}

.challenge .btn {
    border-radius: 5px;
}